[MM-55294] Migrate jest v26 to v29 to speed up "web app CI PR / test" (#25192)

webapp/platform/client/src/setupTests.ts

@@ -1,4 +0,0 @@
-// Copyright (c) 2015-present Mattermost, Inc. All Rights Reserved.
-// See LICENSE.txt for license information.
-
-import 'isomorphic-fetch';