It fixes Rails 5.0 deprecation flooding like:

```
DEPRECATION WARNING: Passing strings or symbols to the middleware builder is deprecated, please change
them to actual class references.  For example:

  "::Gitlab::Middleware::ReadOnly" => Gitlab::Middleware::ReadOnly

 (called from <top (required)> at /builds/gitlab-org/gitlab-ce/config/environment.rb:11)
DEPRECATION WARNING: Passing strings or symbols to the middleware builder is deprecated, please change
them to actual class references.  For example:

  "ActionDispatch::Static" => ActionDispatch::Static

 (called from <top (required)> at /builds/gitlab-org/gitlab-ce/config/environment.rb:11)
DEPRECATION WARNING: Passing strings or symbols to the middleware builder is deprecated, please change
them to actual class references.  For example:

  "Gitlab::Testing::RequestBlockerMiddleware" => Gitlab::Testing::RequestBlockerMiddleware

 (called from <top (required)> at /builds/gitlab-org/gitlab-ce/config/environment.rb:11)
DEPRECATION WARNING: Passing strings or symbols to the middleware builder is deprecated, please change
them to actual class references.  For example:

  "ActionDispatch::Static" => ActionDispatch::Static

 (called from <top (required)> at /builds/gitlab-org/gitlab-ce/config/environment.rb:11)
DEPRECATION WARNING: Passing strings or symbols to the middleware builder is deprecated, please change
them to actual class references.  For example:

  "Gitlab::Testing::RequestInspectorMiddleware" => Gitlab::Testing::RequestInspectorMiddleware

 (called from <top (required)> at /builds/gitlab-org/gitlab-ce/config/environment.rb:11)
```

Resolve "Project search in navbar is missing top margin in dev.gitlab.com"

Closes #47773

See merge request gitlab-org/gitlab-ce!19718

Clean up stale Prometheus metrics in before_exec unicorn hook

See merge request gitlab-org/gitlab-ce!19683

Resolve "Alignment of labels within two column layouts for radio and check boxes"

Closes #47265

See merge request gitlab-org/gitlab-ce!19671

Fix labels too large

Closes #47499 and #47762

See merge request gitlab-org/gitlab-ce!19640

Fixed IDE jobs empty state showing when loading

Closes #47766

See merge request gitlab-org/gitlab-ce!19706

Ensure MR diffs always exist in the PR importer

Closes #47312

See merge request gitlab-org/gitlab-ce!19704

Find and mark more Git disk access locations, part 2

See merge request gitlab-org/gitlab-ce!19437

mergeError message has been binded using v-html directive

See merge request gitlab-org/gitlab-ce!19058

Closes #47766

Replace ... with ellipsis in placeholders

See merge request gitlab-org/gitlab-ce!19627

Bumping gitlab-gollum-lib and gitlab-gollum-rugged_adapter

Closes #47577

See merge request gitlab-org/gitlab-ce!19641

i18n: document how to use links without splitting sentences

See merge request gitlab-org/gitlab-ce!19682

Add CI_{PIPELINE,JOB}_URL

See merge request gitlab-org/gitlab-ce!19618

In rare cases it could happen that an MR was created, but creating the
MR diffs somehow failed (e.g. due to an error). This commit adds an
additional check to make sure MR diffs are always present when importing
GitHub pull requests.

Merge branch 'blackst0ne-rails5-actionview-missingtemplate-in-spec-features-projects-wiki-user_views_wiki_page_spec-rb' into 'master'

Resolve "[Rails5] `ActionView::MissingTemplate` in spec/features/projects/wiki/user_views_wiki_page_spec.rb"

Closes #47738

See merge request gitlab-org/gitlab-ce!19685

Resolve "[Rails5] `ActionView::MissingTemplate` in spec/features/projects/wiki/user_views_wiki_page_spec.rb"

Add CI job to check Gemfile.rails5.lock

See merge request gitlab-org/gitlab-ce!19605

Remove unnecessary and broken example

See merge request gitlab-org/gitlab-ce!19598

Add Gitlab::SQL:CTE for easily building CTE statements

See merge request gitlab-org/gitlab-ce!19652

Qa 112 fix auto devops cluster spec

See merge request gitlab-org/gitlab-ce!19584

Use nip.io instead of xip.io

See merge request gitlab-org/gitlab-ce!19688

Add navigation theme documentation

See merge request gitlab-org/gitlab-ce!19645

Move Gitaly branch/tag/ref RPC's to opt-out

See merge request gitlab-org/gitlab-ce!19644

CE: Unify app/views/ci/variables/_variable_row.html.haml

See merge request gitlab-org/gitlab-ce!19594

Fix width of project avatar in Web IDE

Closes #47696

See merge request gitlab-org/gitlab-ce!19647

Merge branch '47731-update-docs-as-gke-cluster-creation-label-has-changed-from-project-id-to-project' into 'master'

Resolve "Update docs as GKE cluster creation label has changed from "project ID" to "project""

Closes #47731

See merge request gitlab-org/gitlab-ce!19676

Remove favicon-blue.ico because it's no longer used

See merge request gitlab-org/gitlab-ce!19658

Fix typo in doc/development/README.md

See merge request gitlab-org/gitlab-ce!19679