Change the tags query used for OCI to list tags to be shallow

This removes the join on Manifest which was (possibly) causing the prod issue. We also simplify the lookup for pre-OCI as well, a bit.

endpoints/api/test/test_manifest.py

@@ -8,7 +8,7 @@ from test.fixtures import *
 def test_repository_manifest(client):
   with client_with_identity('devtable', client) as cl:
     repo_ref = registry_model.lookup_repository('devtable', 'simple')
-    tags = registry_model.list_repository_tags(repo_ref)
+    tags = registry_model.list_all_active_repository_tags(repo_ref)
     for tag in tags:
       manifest_digest = tag.manifest_digest
       if manifest_digest is None:

endpoints/v2/tag.py

@@ -20,8 +20,7 @@ def list_all_tags(namespace_name, repo_name, start_id, limit, pagination_callbac
 
   # NOTE: We add 1 to the limit because that's how pagination_callback knows if there are
   # additional tags.
-  tags = registry_model.list_repository_tags(repository_ref, start_pagination_id=start_id,
-                                             limit=limit + 1, sort_tags=True)
+  tags = registry_model.lookup_active_repository_tags(repository_ref, start_id, limit + 1)
   response = jsonify({
     'name': '{0}/{1}'.format(namespace_name, repo_name),
     'tags': [tag.name for tag in tags][0:limit],