Move the Hashed storage checks to `gitlab:app:check` task instead of `gitlab:geo:check`
Problem to solve
As part of #25360 (closed) and &2320 we want to make Hashed Storage, the only storage.
In order to make this a requirement, we need to do a bunch of things, including letting a sysadmin know when they still have a repository under legacy storage. We've built this for Geo, as Hashed Storage is a requirement for Geo since a long time.
Intended users
Proposal
What we should do is move those checks out of the Geo scope, and make it run in gitlab:app:check (perhaps also keep it running as part of gitlab:geo:check in the short-term)
What does success look like, and how can we measure that?
In an existing installation, when you run gitlab:app:check and you still have a project using legacy storage, you should get an error message.