Documentation process/policy updates to foster contributions to docs as SSOT

See merge request gitlab-org/gitlab-ce!23951

`--no-rdoc` and `--no-ri` have been deprecated since RubyGems 2.0:
https://github.com/rubygems/rubygems/blob/v2.0.0/History.txt#L43

They were finally removed in a recent release:
https://github.com/rubygems/rubygems/pull/2354

Bump database_cleaner version

Closes #55539

See merge request gitlab-org/gitlab-ce!23985

Merge branch '52888-status-emoji-should-not-be-added-to-awards-section-on-issue-page-2' into 'master'

Resolve "Status emoji should not update awards section on issue page"

Closes #52888

See merge request gitlab-org/gitlab-ce!23470

Fixed content-disposition in blob and files API endpoint

Closes #55781

See merge request gitlab-org/gitlab-ce!24078

Stop using deprecated argument to `gem`

See merge request gitlab-org/gitlab-ce!24079

Add first-class releases API

See merge request gitlab-org/gitlab-ce!23795

`--no-rdoc` and `--no-ri` have been deprecated since RubyGems 2.0:
https://github.com/rubygems/rubygems/blob/v2.0.0/History.txt#L43

They were finally removed in a recent release:
https://github.com/rubygems/rubygems/pull/2354

Update cert-manager chart from v0.5.0 to v0.5.2

Closes #55716

See merge request gitlab-org/gitlab-ce!24025