**Root cause**
ScreenFlashNotificationColorDialogFragment creates Timer which spawns
unmanageable threads for tests. Also, the test itself uses Thread.sleep
which makes it non-destermistic.
Bug: 279082331
Test: atest ScreenFlashNotificationColorDialogFragmentTest --iteration
20
Change-Id: Id49c8d402a0578f8297ca12fe49da304c7a988d8