Merge branch 'backup-delete-all-use-file-join' into 'master'

Use File.join in DeleteAllRepositories test

Closes #47108

See merge request gitlab-org/gitlab-ce!19310

spec/lib/backup/repository_spec.rb

@@ -92,7 +92,7 @@ describe Backup::Repository do
       end
 
       def list_repositories
-        Dir[SEED_STORAGE_PATH + '/*.git']
+        Dir[File.join(SEED_STORAGE_PATH, '*.git')]
       end
     end