Simplifying queries around images and placements

Only verbs needs to load placements for multiple images, so we can vastly simplify and optimize most queries by making it two-step, and having the rest of the image loads not worry about placements

test/test_api_usage.py

@@ -2829,7 +2829,7 @@ class TestListAndDeleteTag(ApiTestCase):
       repository=ADMIN_ACCESS_USER + '/complex', tag='staging'))
 
     staging_images = json['images']
-    assert len(prod_images) == len(staging_images) + 1
+    assert len(prod_images) == len(staging_images) + 2
 
     # Delete prod.
     self.deleteEmptyResponse(RepositoryTag,