CI: use commit SHA in persistent refspec

See merge request gitlab-org/gitlab!51208

A Git fetch refspec normally looks like 'refs/foo/bar:refs/qux/baz'.
In English that means: resolve 'refs/foo/bar' on the remote server,
fetch the object it points to, and create a local reference
'refs/qux/baz' that points to that thing.

However, since Git 1.8.3 (released in 2013) it is also allowed to
write '$COMMIT_SHA:refs/qux/baz'. What that does is: fetch object
$COMMIT_SHA from the server, and create a local 'refs/qux/baz' that
points to that thing.

This commit changes the refspec used for "persistent ref" CI fetches.
We already know what commit SHA persistent refs point to so there is
no need to have Git resolve the persistent ref again during a CI
build.

Enable multipart transfers for S3 copying

See merge request gitlab-org/gitlab!51267

This is a follow-up to
https://gitlab.com/gitlab-org/gitlab/-/merge_requests/50922. Multithreaded,
multipart transfers are only enabled if the file is above 5 GB or the
multipart chunk size is explicitly set.

We now set the chunk size to 10 megabytes (the AWS SDK default) to make
file copies faster.

This commit also updates fog-aws to v3.8.0 to work properly with server
side encryption parameters.

CHANGELOG: https://github.com/fog/fog-aws/blob/master/CHANGELOG.md

Implement declarative enums abstraction

See merge request gitlab-org/gitlab!50698

Update GraphqlExtractor return value to be original hash

See merge request gitlab-org/gitlab!51596

Merge branch '297364-flaky-test-spec-services-merge_requests-export_csv_service_spec-rb-29-mergerequests' into 'master'

test: Fix flaky expectations

See merge request gitlab-org/gitlab!51457

Merge branch '296976-the-open-list-in-boards-with-swimlanes-applied-is-mislabeled-as-backlog' into 'master'

Rename Backlog list to Open for Swimlanes

See merge request gitlab-org/gitlab!51539

Remove merge_ref_auto_sync flag

See merge request gitlab-org/gitlab!51624

Instead of spreading the enum information all around the codebase
between different modules like models and GraphQL types, we can set a
single source of the truth for the Enum values.

To do so, we should promote the enums to be first class members of the
project by giving them a new top level directory to live in.

Remove test_failure_history flag

See merge request gitlab-org/gitlab!51464

Remove github_import_pull_request_reviews feature flag

See merge request gitlab-org/gitlab!51334

Override tertiary button mix blend mode for darkmode

See merge request gitlab-org/gitlab!51349

Reverts !46222 to fix 500 error on project's edit page.

See merge request gitlab-org/gitlab!51662

Update gitlab-experiment to 0.4.5

See merge request gitlab-org/gitlab!51506

This makes two functionally similar but helpful improvements in terms of
more clarity and better behavior when circumventing existing codepaths.

Docs: Clarify merge train requirement for GitLab repo

See merge request gitlab-org/gitlab!51647

Fix issues with IDE commit to new branch

See merge request gitlab-org/gitlab!51654

This reverts commit fcc43e30.

Fix argument type for background migration

See merge request gitlab-org/gitlab!51475

Add Design Sprint Template to issue templates.

See merge request gitlab-org/gitlab!51226

Record action when namespace trial starts

See merge request gitlab-org/gitlab!49351

Add `gl-button` to move issue button in issue sidebar

See merge request gitlab-org/gitlab!51285

- It is important that we update the route to the new
  branch.
- Also, we add a "destroy" event to the root component
  so that the spec can properly dispose of Singleton
  things. Otherwise, specs were bumping into eachother
  because Monaco models were being shared.

This actually caused a number of issues and
left the Web IDE in a broken state.

Trigger empty state only for missing file case

See merge request gitlab-org/gitlab!51653

Merge branch '215309-improve-the-error-message-username-has-already-been-taken-on-user-creation' into 'master'

Improve User username error for namespace conflict

See merge request gitlab-org/gitlab!47537

Convert tabs in navigation_tabs.vue to gl-tabs

See merge request gitlab-org/gitlab!47841

Update JQF ordering and example name

See merge request gitlab-org/gitlab!51607

Geo: Prepare for secondary side verification

See merge request gitlab-org/gitlab!51242

Update default value of applications_settings.max_import_size to 0

See merge request gitlab-org/gitlab!51229