Spike: Add support for the new container registry with metadata DB and online GC on new self-managed installs

Overview

The intent of this issue is to do the initial scoping for the related epic - &22

We need to do an initial spike for the scope of work and begin to draft sub-issues to complete this work.

Context

We're getting close to the completion of the .com container registry upgrade/migration to the new version backed by a metadata DB and online GC (gitlab-org&5523 (closed)). Once we're done with the .com upgrade/migration, we'll focus on doing the same for self-managed.

Problem

To enable the .com migration we had to add support for the registry metadata DB and online GC to Charts. So far, this support remains listed as experimental and not ready for production use.

Additionally, there is no support for the registry metadata DB and online GC in Omnibus and source installs.

In order to enable self-managed customers to migrate to the new registry, we first need to add support for the metadata DB and online GC to all installation types. We then need to mark these features as non-experimental and make them the default for new installs before we start thinking about how to upgrade/migrate the existing installations.

Proposal

I see the following non-exhaustive list of tasks:

1. Add support for the registry metadata DB and online GC to Omnibus and Source installs;
2. Update Charts support so that it's no longer marked as experimental;
3. Enable/setup the metadata DB and online GC features by default for new installs.