Previously if a user enabled consolidated settings then selectively
disabled some object storage types, they were still required to set a
bucket name for that object type. For example:

1. Enable consolidated object storage
(https://docs.gitlab.com/ee/administration/object_storage.html).

2. Configure the artifacts object storage with the below:

```
gitlab_rails['object_store']['objects']['artifacts']['enabled'] = false

gitlab_rails['artifacts_enabled'] = true
```

Reconfigure GitLab and you see this error:

```
Object storage for artifacts must have a bucket specified
```

Since the previous workaround would be to set a dummy bucket name, this
change skips assigning consolidated settings if object storage has been
disabled for a specific type.

Relates to https://gitlab.com/gitlab-org/gitlab/-/issues/233826