Throttle broadcasts of ACTION_EFFECTS_SUPPRESSOR_CHANGED

1) Don't broadcast at all if the set of suppressed effects has changed but not the set of suppressors themselves (e.g. if an NLS changes the hints it provides).
2) Instead of sending it out immediately, wait for 250 ms after the last change (and restart this wait if it changes again).

Bug: 371776935
Test: atest NotificationManagerServiceTest
Flag: com.android.server.notification.nm_binder_perf_throttle_effects_suppressor_broadcast
Change-Id: I48645b08dd80b49729396c85db37525d16949d37