[Gardener] Use sinon.useFakeTimers instead of stubbing setTimeout

The issue is:
* We stub out `setTimeout`, it turns from `trackingSetTimeout` to `stubbedTestTimeout`.
* The test restores it, so it turns to `trackingSetTimeout`.
* On `restoreAll`, `window['setTimeout']` returns to `originalSetTimeout`.
* Calling `sinon.restore()` makes `window['setTimeout']` return to `trackingSetTimeout`.

Then, when we stub out `setTimeout` in `startTrackingAsyncActivity`, the original
is returned as `trackingSetTimeout` whereas it should have returned as `originalSetTimeout`.

Bug: none
Change-Id: I4c0e376368507b16e57b803eff7b5a04d4e9f7f0
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/6926730
Auto-Submit: Ergün Erdoğmuş <[email protected]>
Commit-Queue: Ergün Erdoğmuş <[email protected]>
Commit-Queue: Nikolay Vitkov <[email protected]>
Reviewed-by: Nikolay Vitkov <[email protected]>

Author: ergunsh

front_end/ui/legacy/UIUtils.test.ts

@@ -136,21 +136,20 @@ describe('UIUtils', () => {
 
   describe('LongClickController', () => {
     it('does not invoke callback when disposed', () => {
+      const clock = sinon.useFakeTimers({toFake: ['setTimeout']});
       const el = document.createElement('div');
       const callback = sinon.spy();
       const controller = new UI.UIUtils.LongClickController(el, callback);
-      // @ts-expect-error
-      const setTimeout = sinon.stub(window, 'setTimeout').callsFake(cb => cb());
 
       el.dispatchEvent(new PointerEvent('pointerdown'));
+      clock.runAll();
       sinon.assert.calledOnce(callback);
 
       controller.dispose();
 
       el.dispatchEvent(new PointerEvent('pointerdown'));
       sinon.assert.calledOnce(callback);
-
-      setTimeout.restore();
+      clock.restore();
     });
   });