Fix pagination on sorts with lots of ties

## What does this MR do?

Fixes #18915. As we only order by the sorted column, we don't have any tie-breaker. Some orderings, like priority and weight, have lots of ties, so you can see duplicate results as you page through. (Timestamp columns are less susceptible to this.)

## Are there points in the code the reviewer needs to double check?

I just picked `id DESC`, this could as easily be `id ASC`.

## Why was this MR needed?

Postgres and MySQL don't guarantee that pagination with `LIMIT` and
`OFFSET` will work as expected if the ordering isn't unique. From the Postgres docs:

> When using `LIMIT`, it is important to use an `ORDER BY` clause that
> constrains the result rows into a unique order. Otherwise you will get
> an unpredictable subset of the query's rows

Before:

    [1] pry(main)> issues = 1.upto(Issue.count).map { |i| Issue.sort('priority').page(i).per(1).map(&:id) }.flatten
    [2] pry(main)> issues.count
    => 81
    [3] pry(main)> issues.uniq.count
    => 42

After:

    [1] pry(main)> issues = 1.upto(Issue.count).map { |i| Issue.sort('priority').page(i).per(1).map(&:id) }.flatten
    [2] pry(main)> issues.count
    => 81
    [3] pry(main)> issues.uniq.count
    => 81

See merge request !4878

Fix clickable code search results

Closes #17860

See merge request !4654

Postgres and MySQL don't guarantee that pagination with `LIMIT` and
`OFFSET` will work if the ordering isn't unique. From the Postgres docs:

> When using `LIMIT`, it is important to use an `ORDER BY` clause that
> constrains the result rows into a unique order. Otherwise you will get
> an unpredictable subset of the query's rows

Before:

    [1] pry(main)> issues = 1.upto(Issue.count).map { |i| Issue.sort('priority').page(i).per(1).map(&:id) }.flatten
    [2] pry(main)> issues.count
    => 81
    [3] pry(main)> issues.uniq.count
    => 42

After:

    [1] pry(main)> issues = 1.upto(Issue.count).map { |i| Issue.sort('priority').page(i).per(1).map(&:id) }.flatten
    [2] pry(main)> issues.count
    => 81
    [3] pry(main)> issues.uniq.count
    => 81

Remove Rubocop skip comment from migration style guide

This was an error in previous MR https://gitlab.com/gitlab-org/gitlab-ce/merge_requests/4693

[ci skip]

See merge request !4879

Fix errors found on importing GitLab CE repo

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/18968

See merge request !4855

Use influxdb-management for managing InfluxDB

## What does this MR do?

This updates the InfluxDB documentation so it suggests using https://gitlab.com/gitlab-org/influxdb-management instead of requiring users to manually copy-paste queries into an InfluxDB shell.

## Are there points in the code the reviewer needs to double check?

Mostly spelling and if the writing style makes sense.

## Why was this MR needed?

The same list of queries was duplicated in multiple places and it was hard to manually keep this up to date.

## Does this MR meet the acceptance criteria?

- [x] ~~[CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added~~ Not really tied into a version
- [x] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4875

Add Sidekiq job latency to transaction metrics.

See merge request !4871

This removes the need for manually updating the list of queries every
time we make a change.

[ci skip]

Updated InfluxDB continuous queries for 8.9.0

See merge request !4872

[ci skip]

Added bottom padding to label color suggestion link

## What does this MR do?

Adds a bottom margin to label color suggestions to make sure that when wrapped there is enough whitespace between color rows.

## Are there points in the code the reviewer needs to double check?

😕 

## Why was this MR needed?

Mobile UX.

## What are the relevant issue numbers?

Closes #18857.

## Screenshots (if relevant)

![Screen_Shot_2016-06-22_at_00.31.26](/uploads/f49c7fa2b97b13e69f0dea97c5dfb319/Screen_Shot_2016-06-22_at_00.31.26.png)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [ ] [Documentation created/updated](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/doc/development/doc_styleguide.md)
- [ ] API support added
- Tests
  - [ ] Added for this feature/bug
  - [ ] All builds are passing
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

See merge request !4845

Restrict header logo to 36px so it doesn't overflow.

## What does this MR do?

Fixes the logo in the header.

## Are there points in the code the reviewer needs to double check?

I don't think so.

## Why was this MR needed?

Logos that weren't 36px by 36px were broken in 8.9.0

## What are the relevant issue numbers?

Fixes #18980

## Screenshots (if relevant)

Before:

![Screen_Shot_2016-06-22_at_1.52.54_PM](/uploads/de6e4d9ccf40b972565e3864173a9907/Screen_Shot_2016-06-22_at_1.52.54_PM.png)

After:

![Screen_Shot_2016-06-22_at_1.52.37_PM](/uploads/d72e015263888b5155c1db5e25f54d66/Screen_Shot_2016-06-22_at_1.52.37_PM.png)

## Does this MR meet the acceptance criteria?

- [ ] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- [x] Conform by the [style guides](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CONTRIBUTING.md#style-guides)
- [x] Branch has no merge conflicts with `master` (if you do - rebase it please)
- [x] [Squashed related commits together](https://git-scm.com/book/en/Git-Tools-Rewriting-History#Squashing-Commits)

cc: @jschatz1 @dzaporozhets @rspeicher 

See merge request !4861

Add caching for Ruby 2.3 tests.

Accidentally removed when !3807 was merged.

See merge request !4868

Add Subresource Integrity attribute to CSS and JS assets.

This prevents compromised or malicious CDNs from modifying GitLab's assets. The hash provided by Rails is compared to the hash of the asset the browser has downloaded. The browser will refuse to execute/parse the assets if the hashes don't match. SRI is currently implemented in Firefox, Chrome, and Opera.

This doesn't apply to the dynamically-generated per-page JavaScript due to [a bug in sprockets-rails](https://github.com/rails/sprockets-rails/issues/359). Unfortunately until there's a fix available we won't benefit fully from a security perspective.

It's more secure. More information is available in #18230 and on MDN:
https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity

Fixes #18230

See merge request !4808

Accidentally removed when !3807 was merged.

This prevents compromised or malicious CDNs from modifying assets. The hash provided by Rails is compared to the hash of the asset the browser has downloaded. The browser will refuse to execute/parse the assets if the hashes don't match. SRI is currently implemented in Firefox, Chrome, and Opera.

More information is available in #18230 and on MDN: https://developer.mozilla.org/en-US/docs/Web/Security/Subresource_Integrity

This doesn't apply to the dynamically-generated per-page JavaScript due to a bug in sprockets-rails (https://github.com/rails/sprockets-rails/issues/359).

Fix subsequent SAML sign ins

Fixes a bug when `auto_link_ldap_user` is `true` that causes SAML users to be unable to sign in a second time.

Fix the problem for https://gitlab.zendesk.com/agent/tickets/22546

See merge request !4718

Handle external issues in IssueReferenceFilter

Handling of external issues was broken when I refactored
`IssueReferenceFilter` to use fewer SQL queries.

Fixes #18827

See merge request !4789

Update docs based on customer upgrade from 4.0

## What does this MR do?

Adds helpful notes to early upgrade docs. Without these helpful hints it will be really hard for most people to upgrade from early versions to later versions. 

The tip about doing database migrations to version 6.1, then migrating iids, then migrating the database all the way was based on a tip from https://github.com/gitlabhq/gitlabhq/issues/7869. It worked really well!


See merge request !4409

Update Todos documentation and screenshots to include new functionality.

Updates documentation for todos, includes updated and new screenshots.

See also !4502 and #18906 

Closes #18923

[ci skip]

See merge request !4840

Time for 8.10.0-pre

See merge request !4852

Hide nav arrows by default

## What does this MR do?
- Fixes the arrow icon flashing on page load
- Removes settings dropdown at higher breakpoint
- Removes unneeded CSS

Closes #18941

## Screenshots (if relevant)
Arrow flashing bug:    
![icon](/uploads/3db95626acd0adb37438bdbc2c4aa154/icon.gif)

Settings dropdown breaking nav:    
<img src="/uploads/4351035f4cf8cb9fd892b621e6339e50/Screen_Shot_2016-06-21_at_4.25.50_PM.png" width="800px">

@alfredo1 would you mind double checking this to make sure the arrow flashing is definitely not happening? 

See merge request !4843

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

[ci skip]
Signed-off-by: Rémy Coutable <remy@rymai.me>

Refactor labels docs

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/18555

See merge request !3347