Consolidate all object storage configuration: only one bucket

This is a follow-up to #23345 (closed)

Today installing GitLab requires up to 13 different buckets, this adds a lot of friction to new installations as well as slowing down feature adoption.

Thanks to consolidated object storage configuration, developed in #23345 (closed) we now support one single credential for all the buckets.

The next step will be to use just one bucket.