wm: Speculative fix for window blurring after alt tabbing

Could not repro consistently locally, but it should be related to the
occlusion pauser. I'm not sure why its not detecting the animation end,
but perhaps the users are somehow triggering alt tab without an
animation start. Lower the timeout and see if there's any effect on
alt tab performance.

Test: none
Bug: b/335329932
Change-Id: I40116326415f499a673ae41548697d4f831ad098
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5827927


Reviewed-by: Sophie Wen <sophiewen@chromium.org>
Commit-Queue: Sammie Quon <sammiequon@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1349488}