Make deleting a group compatible with ocs v2

Signed-off-by: Joas Schilling <coding@schilljs.com>

apps/provisioning_api/lib/Controller/GroupsController.php

@@ -164,7 +164,7 @@ class GroupsController extends OCSController {
 			throw new OCSException('', 102);
 		}
 
-		return new DataResponse(null, 100);
+		return new DataResponse();
 	}
 
 	/**