Geo exposes repository storage paths in HTTP API

As part of the Gitaly migration, I'm working on flagging all references to repository storage paths in gitlab-rails for removal. Once the Gitaly migration is complete, it will be opaque to gitlab-rails in what absolute directories repositories are stored.

It seems that Geo exposes repository storage paths via an HTTP API: https://gitlab.com/gitlab-org/gitlab-ee/blob/21158b9dd5a9a501cfae4560a1b5ba8d727ed6bd/ee/app/serializers/storage_shard_entity.rb

This is something we will have to stop doing, because Geo sits in gitlab-rails, where it cannot know those paths.