forgot a table suffix, fix activitylog test

apps/devhub/models.py

@@ -227,7 +227,7 @@ class ActivityLogManager(amo.models.ManagerBase):
     def _by_type(self, webapp=False):
         qs = super(ActivityLogManager, self).get_query_set()
         table = (table_name('log_activity_app') if webapp
-                 else 'log_activity_addon')
+                 else table_name('log_activity_addon'))
         return qs.extra(
             tables=[table],
             where=['%s.activity_log_id=%s.id'