Geo: Possible bug in backfilling Container Repository

In !107421 (merged), RepositoryRegistrySyncWorker uses container_repositories_max_capacity because it is intended to schedule container repository sync jobs for backfilling, retrying failures, and to cover any rare lost events.

However based on reading the code, I think it is not handling container repositories, and is only handling Git repositories. This makes sense long-term. But to resolve the current bug, we could force it to handle container repositories as well for now.