Bug 1704338. Use promiseApzFlushedRepaints instead of promiseOnlyApzControllerFlushed in doubleTapOn. r=botond

No reason to only wait for the controller, I think we want to wait for the full repaint. Seems to make things less intermittent, the test in bug 1702464 was already using this.

Differential Revision: https://phabricator.services.mozilla.com/D111554

gfx/layers/apz/test/mochitest/apz_test_native_event_utils.js

@@ -1369,5 +1369,5 @@ async function doubleTapOn(element, x, y, useTouchpad) {
   await transformEndPromise;
 
   // Flush state so we can query an accurate resolution
-  await promiseOnlyApzControllerFlushed();
+  await promiseApzFlushedRepaints();
 }