Ensure current user can retry a build before showing the 'Retry' button

## What does this MR do?

Fixes #20150.

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] 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 !5476

Add support for using RequestStore within Sidekiq tasks via SIDEKIQ_REQUEST_STORE env variable

See merge request !5054

Add missing escape at line end

Documentation fix, pretty simple.

See merge request !5422

Signed-off-by: Rémy Coutable <remy@rymai.me>

Merge branch '20189-markdown-video-doesn-t-work-when-the-referenced-video-file-is-in-same-repo' into 'master'

Ensure relative paths for video are rewritten as we do for images

## What does this MR do?

This ensures that path to videos are rewritten as we do for images.

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

I've decided to add a new `Blob#video?` method for simplicity's sake but this should probably be added to `Gitlab::Git::Blob`.

## What are the relevant issue numbers?

Fixes #20189.

## Does this MR meet the acceptance criteria?

- [x] [CHANGELOG](https://gitlab.com/gitlab-org/gitlab-ce/blob/master/CHANGELOG) entry added
- Tests
  - [x] 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 !5474

Signed-off-by: Rémy Coutable <remy@rymai.me>

Signed-off-by: Rémy Coutable <remy@rymai.me>

Disable MySQL foreign key checks before dropping all tables

Fixes #20237. Disables MySQL foreign key checks before dropping all tables in a restore. MySQL doesn't honor `CASCADE` without a special flag when the database/tables are created. In order to drop the tables we need to disable foreign key checks. After the drop, re-enable the key checks. 

WIP: Pending confirmation from customer that this fix works. 

See merge request !5472

This significantly reduces the DB churn in the PostReceive task when it
performs reference extraction.

See #18663

Added '*.js.es6 gitlab-language=javascript' to .gitattributes

## What does this MR do?

According to the branch name this adds the `sytanx` highlighting for `.js.es6` files, but this actually adds the `syntax` highlighting. 😆 

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

Is this the right place? 🏃 

## Why was this MR needed?

We need pretty ES6 diffs.

## What are the relevant issue numbers?

Flyin' solo 🛫 

## Screenshots (if relevant)

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

See merge request !5486