Switch back to the read-then-write tag deletion code

We changed to this originally to avoid locks

data/model/tag.py

@@ -100,11 +100,16 @@ def delete_tag(namespace_name, repository_name, tag_name):
 def garbage_collect_tags(repo):
   expired_time = get_epoch_timestamp() - repo.namespace_user.removed_tag_expiration_s
 
-  (RepositoryTag
-    .delete()
+  tags_to_delete = list(RepositoryTag
+                        .select(RepositoryTag.id)
                         .where(RepositoryTag.repository == repo,
                                ~(RepositoryTag.lifetime_end_ts >> None),
                                (RepositoryTag.lifetime_end_ts <= expired_time))
+                        .order_by(RepositoryTag.id))
+  if len(tags_to_delete) > 0:
+    (RepositoryTag
+     .delete()
+     .where(RepositoryTag.id << tags_to_delete)
      .execute())