Try solving flaky unit test by switch to use different implementation of setImmediate (#5655)

Signed-off-by: Janne Savolainen <janne.savolainen@live.fi>

src/common/test-utils/flush-promises.ts

@@ -2,4 +2,6 @@
  * Copyright (c) OpenLens Authors. All rights reserved.
  * Licensed under MIT License. See LICENSE in root directory for more information.
  */
-export const flushPromises = () => new Promise(resolve => setTimeout(resolve, 0));
+import { setImmediate } from "timers";
+
+export const flushPromises = () => new Promise(setImmediate);