Change back to overridden merge

Author: boie0025

lib/active_admin/mongoid/helpers/collection.rb

@@ -9,7 +9,7 @@ def collection_size(collection=collection)
         if collection.is_a?(::Mongoid::Criteria)
           collection.count(true)
         else
-          collection.count
+          original_collection_size(collection)
         end
       end