Fix group destroy not working with Gitaly Cluster

Previously when a namespace was deleted, it would always attempt to
remove the legacy storage path. For example, for namespace `test-group`,
Rails would issue a removal for `/path/to/test-group` just in case there
is data there.

If the path does not exist, Gitaly raises an Invalid Argument GRPC (3)
exception, but Gitaly Cluster raises an Internal error (13).

Since hashed storage is now the default and the legacy path shouldn't be
used at all, we can avoid this error entirely by not attempting to
delete the legacy path.

Closes https://gitlab.com/gitlab-org/gitlab/-/issues/276501

app/models/concerns/storage/legacy_namespace.rb

@@ -90,7 +90,7 @@ module Storage
     end
 
     def old_repository_storages
-      @old_repository_storage_paths ||= repository_storages
+      @old_repository_storage_paths ||= repository_storages(legacy_only: true)
     end
 
     def repository_storages(legacy_only: false)

changelogs/unreleased/sh-hashed-storage-no-destroy-namespace-dir.yml

+---
+title: Fix group destroy not working with Gitaly Cluster
+merge_request: 46934
+author:
+type: fixed

spec/models/namespace_spec.rb

@@ -687,7 +687,7 @@ RSpec.describe Namespace do
       let!(:project) { create(:project_empty_repo, namespace: namespace) }
 
       it 'has no repositories base directories to remove' do
-        allow(GitlabShellWorker).to receive(:perform_in)
+        expect(GitlabShellWorker).not_to receive(:perform_in)
 
         expect(File.exist?(path_in_dir)).to be(false)