Upload files through the multi-file editor

Closes #38629 and #38614

See merge request gitlab-org/gitlab-ce!14975

Merge branch '39593-emails-on-push-are-sent-to-only-the-first-recipient-when-using-aws-ses' into 'master'

Resolve "Emails on Push are sent to only the first recipient when using AWS SES"

Closes #39593

See merge request gitlab-org/gitlab-ce!15083

Resolve "Convert autosize.js library to be a Yarn managed library"

Closes #39616

See merge request gitlab-org/gitlab-ce!15087

Revert "Merge branch '2518-saved-configuration-for-issue-board' into 'master'"

See merge request gitlab-org/gitlab-ce!15092

This reverts merge request !15009

Enable NestingDepth (level 6) on scss-lint

Closes #39582

See merge request gitlab-org/gitlab-ce!15073

Refresh open Issue and Merge Request project counter caches when re-opening

Closes #39583

See merge request gitlab-org/gitlab-ce!15085

Fix broken Members link when relative URL root paths are used

See merge request gitlab-org/gitlab-ce!15070

Resolve "Performance bar appears enabled even though it won't show up"

Closes #39570

See merge request gitlab-org/gitlab-ce!15084

Signed-off-by: Rémy Coutable <remy@rymai.me>

Signed-off-by: Rémy Coutable <remy@rymai.me>

Remove code from global namespace

See merge request gitlab-org/gitlab-ce!15058

Update i18n in FE docs for marking and interpolation

See merge request gitlab-org/gitlab-ce!15020

Fix call stack size exceeded group milestone description autocomplete

Closes #39020

See merge request gitlab-org/gitlab-ce!14972

The emails on push feature reuses the same email object, to avoid the expensive
work of generating the email body.

This interceptor would previously set multiple values for the same header, as
that's the mail gem's default behaviour when called with the same header more
than once.

We don't want to change the emails on push service (although it's the only place
where this happens), but fixing the interceptor is just as sensible anyway.

Merge branch 'pawel/bump_prometheus_gem_to_fix_read_all_values_returning_bad_data-39504' into 'master'

Update Prometheus Gem to fix problem caused by using wrong data offsets

See merge request gitlab-org/gitlab-ce!15081

Changed project select to use it independently and not onlt as a combobutton

See merge request gitlab-org/gitlab-ce!15043

Fix 500 error for old (somewhat) MRs

Closes #36540

See merge request gitlab-org/gitlab-ce!14945

Upgrade Gitaly to v0.50.0

See merge request gitlab-org/gitlab-ce!15050

Merge branch '39054-activerecord-statementinvalid-pg-querycanceled-error-canceling-statement-due-to-statement-timeout' into 'master'

Resolve "ActiveRecord::StatementInvalid: PG::QueryCanceled: ERROR:  canceling statement due to statement timeout"

Closes #39054

See merge request gitlab-org/gitlab-ce!15063

Add docs for backing up to Google Cloud Storage

See merge request gitlab-org/gitlab-ce!15074

Add missing circuitbreaker metrics to prometheus documentation

See merge request gitlab-org/gitlab-ce!15062

* master: (51 commits)
  Move locked check to a guard-clause
  Ci::Build tag is a trait instead of an own factory
  [CE backport] Saved configuration for issue board
  Use the correct project visibility in system hooks
  Add changelog
  more readable changelog
  Make merge_jid handling less stateful in MergeService
  Fetch the merged branches at once
  remove extra whitespace
  use a delegate for `username` to be more future friendly
  Merging EE doc into CE
  add changelog entry
  Avoid using Rugged in Gitlab::Git::Wiki#preview_slug
  Cache commits on the repository model
  Remove groups_select from global namespace & simplifies the code
  Change default disabled merge request widget message to "Merge is not allowed yet"
  Semi-linear history merge is now available in CE.
  Remove repetitive karma spec
  Improve spec to check hidden component
  Rename to shouldShowUsername
  ...

Ci::Build tag is a trait instead of an own factory

See merge request gitlab-org/gitlab-ce!15077

Fix widget of locked merge requests not being presented

See merge request gitlab-org/gitlab-ce!15069

Minor annoyance of mine, and there were a couple of things wrong, for
example:
1. Switching on a property is just a trait
2. It didn't inherrit from its parent

Find and replace through the code based fixed all occurances.

[CE backport] Saved configuration for issue board

See merge request gitlab-org/gitlab-ce!15009