Resolve "Docs update - adding project txt to match up with image"

Closes #53894

See merge request gitlab-org/gitlab-ce!23008

Improve the 'Testing levels' documentation

Closes gitlab-org/quality/team-tasks#24

See merge request gitlab-org/gitlab-ce!21505

Align all avatars and system notes in discussion

See merge request gitlab-org/gitlab-ce!22994

Refactoring Issues::MoveService (port of promote epics)

See merge request gitlab-org/gitlab-ce!22766

Fix tags for environments

Closes gitlab-ee#8397

See merge request gitlab-org/gitlab-ce!22993

Make sure there's only one slash as path separator

Closes #53180

See merge request gitlab-org/gitlab-ce!22954

This reverts commit c739b8e0.

Fix MergeRequestService erroring out on deleted branch

Closes #53853

See merge request gitlab-org/gitlab-ce!22989

Disable CODEOWNERS for the time being

See merge request gitlab-org/gitlab-ce!22991

When a branch is deleted, the push commit IDs is an empty array.
The previous change would attempt to call `[].exists?`, which is
invalid. Fix this by returning `MergeRequestDiffCommit.none` instead.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/53853

Removes feature flag for ciEnvironmentsStatusChanges

Closes #52937

See merge request gitlab-org/gitlab-ce!22947

We can move the file back to its original location once https://gitlab.com/gitlab-org/gitlab-ee/issues/8396 is fixed.

Bump redis-store to 1.6.0

See merge request gitlab-org/gitlab-ce!22963

Bump mime-types to 3.2.2

See merge request gitlab-org/gitlab-ce!22957

Comment on any expanded diff line on MRs (with feature-flag)

Closes #13950

See merge request gitlab-org/gitlab-ce!22914

Set an empty entrypoint for license_management job

Closes #53786

See merge request gitlab-org/gitlab-ce!22955

Remove unnecessary job dependencies

See merge request gitlab-org/gitlab-ce!22961

Changed diff tree filtering to path

Closes #53781

See merge request gitlab-org/gitlab-ce!22978

Improve initial rendering of discussion notes

See merge request gitlab-org/gitlab-ce!22607

Previously it was using name which could make it hard
to filter for the file you want in a certain folder.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/53781

Upgrade whitequark/parser to 2.5.3.0

See merge request gitlab-org/gitlab-ce!22984

Docs: updates docs development guidelines

Closes #53160 and #53115

See merge request gitlab-org/gitlab-ce!22813

Dangerbot: mention tech writers based on DevOps stage

See merge request gitlab-org/gitlab-ce!22945

Bump Sidekiq and other related gems

See merge request gitlab-org/gitlab-ce!22956

Rails 5 counterpart to the version update from
7fb30b4c

Fix  ./spec/features/issues/user_views_issue_spec.rb

Closes gitlab-ee#8390

See merge request gitlab-org/gitlab-ce!22976

Add Discord integration

Closes #21635

See merge request gitlab-org/gitlab-ce!22684

Disable usage pings in review apps

See merge request gitlab-org/gitlab-ce!22965

Merge branch '53082-gitlab-ce-11-4-0-gemfile-conflict-gitlab-markup-and-github-markup' into 'master'

Update gitlab-markup gem to avoid binary name collision

Closes #53082

See merge request gitlab-org/gitlab-ce!22960

Fix some links and Markdown

See merge request gitlab-org/gitlab-ce!22972