* remove feature flag for admin settings
* remove feature flag for domain settings

Suggests to use a JSON structured log instead

Related to https://gitlab.com/gitlab-org/gitlab-ce/issues/54102

This MR introduces tracking of the `rebase_jid` for merge requests. As
with `merge_ongoing?`, `rebase_in_progress?` will now return true if a
rebase is proceeding in sidekiq.

After one release, we should remove the Gitaly-based lookup of rebases.
It is much better to track this kind of thing via the database.

- Add two new ActiveRecord models:
  - RootNamespaceStoragestatistics will persist root namespace statistics
  - NamespaceAggregationSchedule will save information when a new update
to the namespace statistics needs to be scheduled
- Inject into UpdateProjectStatistics concern a new callback that will
call an async job to insert a new row onto NamespaceAggregationSchedule
table
- When a new row is inserted a new job is scheduled. This job will
update call an specific service to update the statistics and after that
it will delete thee aggregated scheduled row
- The RefresherServices makes heavy use of arel to build composable
queries to update Namespace::RootStorageStatistics attributes.
- Add an extra worker to traverse pending rows on
NAmespace::AggregationSchedule table and schedule a worker for each one
of this rows.
- Add an extra worker to traverse pending rows on
NAmespace::AggregationSchedule table and schedule a worker for each one
of this rows

Also add ::Gitlab::LetsEncrypt.enabled? shortcut
and simplify it a lot

Add index for pages domain ssl auto renewal
Add PagesDomain.needs_ssl_renewal scope
Add cron worker for ssl renewal
Add worker for ssl renewal
Add pages ssl renewal worker queues settings

Remove deprecated call in BuildSuccessWorker

Closes #63622

See merge request gitlab-org/gitlab-ce!29958

Enable JIT Kubernetes resource creation for project level clusters

See merge request gitlab-org/gitlab-ce!29515

We now create_deployment on Ci::Build create.
No need to call create_deployment again