Ensure omnibus-gitlab components work properly with Ruby 3

Follow up to #6286 (closed).

With !6383 (merged) we now have ability to use Ruby 3 in the package, and with gitlab!100506 (merged) we will be periodically building such packages.

Before we make Ruby 3 default, we need to confirm various components included in omnibus-gitlab packages (that use Ruby) works fine with Ruby 3. Of these the rails app will be probably covered by work already happening/happened in &5149 (closed), and we need to cover other components (Chef, for example).

This involves deploying various GitLab instances (single node, multi-node HA instances, etc.) with these packages and ensure the functionality exists as expected.