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

CI randomly fails with:
    ActiveRecord::RecordNotFound:
       Couldn't find Project with 'id'=724

This is probably caused by DB cleanup strategy used for :js
tests in combination with `set`.

Update URLs to better ones

See merge request gitlab-org/gitlab-ce!22931

Fix link for raising helm chart issues

See merge request gitlab-org/gitlab-ce!22970

Add link in K8s integration docs to RBAC roles

See merge request gitlab-org/gitlab-ce!22941

Docs: Update Variable naming

See merge request gitlab-org/gitlab-ce!22352

See https://gitlab.com/gitlab-org/gitlab-ce/issues/53082

Fix error handling bugs in kubernetes integration

See merge request gitlab-org/gitlab-ce!22922

This version supports SSL/TLS via the redis:// URL scheme:
https://github.com/redis-store/redis-store/blob/master/CHANGELOG.md

Part of https://gitlab.com/gitlab-org/gitlab-ce/issues/47702