CE backport for changes in EE MR 14017

See merge request gitlab-org/gitlab-ce!29328

This backports to CE changes to allow the EE model
DesignManagement::Repository to override the #attributes_at method to
provide its own git attributes.

The #attributes_at method was freely available, as it's never called by
anything in the app. It looks like the code that called it got
refactored out of existence in ca66a04f. It was still being called in a
spec
https://gitlab.com/gitlab-org/gitlab-ce/blob/85b29c1c2fa3b94d7371cf454c485457a0756cb1/spec/services/files/create_service_spec.rb#L40
which I've left because with the change in Lfs::FileTransformer in fact
is now again the perfect test!

See EE MR
https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/14017

And these comment threads
https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/13894#note_178002089
https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/13894#note_178049984

Fix Double Border in Profile Page

Closes #63227

See merge request gitlab-org/gitlab-ce!29784

Fix nested lists unnecessary margin

Closes #33744

See merge request gitlab-org/gitlab-ce!29775

Add watch option to test script

See merge request gitlab-org/gitlab-ce!29560

Use NotesFinder to get Noteable

See merge request gitlab-org/gitlab-ce!28205

Use @vue/test-utils for tooltip_on_truncate_spec

See merge request gitlab-org/gitlab-ce!29249

Only support postgresql (minimal version)

See merge request gitlab-org/gitlab-ce!29790

Added forked projects API call function

See merge request gitlab-org/gitlab-ce!29841

Fix syntax coloring on emacs

See merge request gitlab-org/gitlab-ce!29844

Fix typo in doc/user/project/pipelines/settings.md

See merge request gitlab-org/gitlab-ce!29851

Change automaticallyl -> automatically

Backport EE MR

See merge request gitlab-org/gitlab-ce!29853

When using suggestions, squash must be enabled

See merge request gitlab-org/gitlab-ce!29687

https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/14280

Run static memory benchmarks from 'derailed_benchmarks' in CI

See merge request gitlab-org/gitlab-ce!29618

Resolve "Username availability checker breaks inline validation"

Closes #62980

See merge request gitlab-org/gitlab-ce!29678

Knative version bump 0.5 -> 0.6

See merge request gitlab-org/gitlab-ce!28798

Now MySQL is no longer supported, we need to change the docs

MySQL support has been removed

Adds missing class in collapsible sections

Closes #63417

See merge request gitlab-org/gitlab-ce!29804

Backport of 12014-incremental-es-wiki-updates

See merge request gitlab-org/gitlab-ce!29531

Docs: Correct upgrade guides for 12.0

See merge request gitlab-org/gitlab-ce!29846

So funny story, true story. I tried to run the test locally, but
didn't make it past setting up Gitaly.

Here's what I tried:

First attempt:

`git clone gitlab-ce`
`cd gitlab-ce && bundle install`
`be rspec`

This didn't work because I was missing the config/database.yml, I
didn't see a `script/bootstrap` so I looked in the readme which
redirected me to a webpage which redirected me to the
gitlab-development-kit.

Second attempt:

`gem install gitlab-development-kit`
cd gitlab-development-kit
gdk init
gdk isntall

This broke somwhere along the way because it couldn't install Gitaly
because my go version was too low. But it did clone the gitlab repo
again and this time it did have a config/database.yml.

So I tried to cd into it and `be rspec
spec/lib/gitlab/database/migration_helpers_spec.rb` which complained
about the database not being configured so I:

- Changed the socket to localhost (in the config/database.yml)
- `createdb <dev_db>` `createdb test_db`
- `be rake db:test:prepare`

Great success, it was doing things! But then failed when it came at
the Gitaly step.

Since I only want to change these three lines, at the point I gave up
and entrusted the pipeline to do its thing.

What I would have liked:

- A 'It's a Rails system, I know this' readme/docs (It's in there
  somewhere just couldn't find it)
- A way to run tests without having to use Gitaly
- Not having too install all the things for a small fix (I get why'd
  you want this, but to me it's overkill)

It's fine to upgrade from 11.11.x to 12.x, so we remove the requirement
to first upgrade to 12.0.x.

Will apply identation from
CSS to collapsible sections

Merge branch '63399-intermittent-spec-failure-in-spec-models-ci-pipeline_schedule_spec-rb-131' into 'master'

Resolve "Intermittent spec failure in spec/models/ci/pipeline_schedule_spec.rb:131"

Closes #63399

See merge request gitlab-org/gitlab-ce!29838

Refactor file locking docs

See merge request gitlab-org/gitlab-ce!29686

- Remove outdated 'introduced in' section
- Update/remove images

The rather cryptic:

      "fk_#{Digest::SHA256.hexdigest("#{table}_#{column}_fk").first(10)}"

Was too much for emacs too handle*, since it was coming from the Rails
codebase I took their way of doing the same thing and applied it here.

I think it's easier to read and it also makes emacs render the
migration helpers pretty again.

* not true, emacs can handle anything, leave emacs alone!

Part of https://gitlab.com/gitlab-org/gitlab-ce/issues/58583

Fixes flaky master

Two static memory benchmarks will be included in our CI pipeline. It
will load gems from the Gemfile and check the amount of RAM consumed
as well as the number of objects allocated and retained.
Aggregated values will be included as 'metrics' into MRs while full
reports will be downloadable as job artifacts.