Remove mentions of non-consolidated object storage for services that support it

Problem to solve

In 13.11, we introduced the consolidated object storage, something that simplifies the configuration of object storage of all the services that support it.

The problem is that we still document the old way of configuring the object storage, which is specific to each service. This complicates things and makes the pages big and hard to scan. We do say that we recommend the consolidated form, so why also have the specific ones as well?

Proposal

Remove mentions of non-consolidated object storage for services that support it. From the table in https://docs.gitlab.com/ee/administration/object_storage.html#storage-specific-configuration, the services that don't support the consolidated form are:

Backups
Container Registry
Mattermost (they have their own config)
Runner caching

For the rest, clean up the docs and remove the specific storage information:

Edited Jan 08, 2023 by Achilleas Pipinellis