Add documentation about backporting changes from EE to CE

See merge request gitlab-org/gitlab-ce!18003

Always allow the performance bar to be enabled for admins

See merge request gitlab-org/gitlab-ce!18137

Replace the `project/issues/labels.feature` spinach test with an rspec analog

See merge request gitlab-org/gitlab-ce!18126

Resolve "Wrong user in push notification email"

Closes #44921

See merge request gitlab-org/gitlab-ce!18148

This was sending the current user, which is the recipient! It should be the user
who pushed the commits.

Do not retry package-and-qa manual action on failure

Closes #44882

See merge request gitlab-org/gitlab-ce!18130

Replace the `project/issues/issues.feature` spinach test with an rspec analog

See merge request gitlab-org/gitlab-ce!17950

Move Sidekiq exporter logs to log/sidekiq_exporter.log

See merge request gitlab-org/gitlab-ce!18127

[Rails5] Isolate `test_after_commit` gem

See merge request gitlab-org/gitlab-ce!18129

Backport missing object storage worker specs

See merge request gitlab-org/gitlab-ce!18138

Refactor the browser performance testing docs

See merge request gitlab-org/gitlab-ce!18097

Raise more descriptive errors when URLs are blocked

See merge request gitlab-org/gitlab-ce!18058

Resolve "Clicking confidential and lock icons on sidebar should also activate dropdown"

Closes #40907

See merge request gitlab-org/gitlab-ce!17869

Add button type to settings toggle

Closes #44737

See merge request gitlab-org/gitlab-ce!18134

Update brakeman to 4.2.1

Closes #44878

See merge request gitlab-org/gitlab-ce!18122

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

The Sidekiq exporter logs were mixing with the normal Sidekiq logs. In order
to support structured logging in Sidekiq, we either need to split this data
out or convert the exporter to produce structured logs. Since Sidekiq job
processing is fundamentally different information from Web server traffic,
it seems cleaner to move the metrics traffic into a separate file, where they
can be parsed by a different filter if needed.

Relates to #20060

Provide clarification on mirrored repositories for pipelines

See merge request gitlab-org/gitlab-ce!18105

Refactor the LFS S3 docs

See merge request gitlab-org/gitlab-ce!18029

Prettify mock data files

See merge request gitlab-org/gitlab-ce!18091

Backport changes in EE MR 4972: System Header and Footer

See merge request gitlab-org/gitlab-ce!18001

Add pagination docs to commit status API

See merge request gitlab-org/gitlab-ce!18124

Handle CR-LFs properly in .gitmodules file

Closes #2262

See merge request gitlab-org/gitlab-ce!18117

[CE] Backport SAML settings changes (Adds validators and rack cookie helper)

See merge request gitlab-org/gitlab-ce!18033

These changes are backported from EE, related to SAML settings in
https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/4549

Resolve "Migrate upload task fails for Groups"

Closes #44776

See merge request gitlab-org/gitlab-ce!18088