make IStatusBarService:onNotificationClear calls async

Blocking binder calls to IStatusBarService:onNotificationClear during
important system transitions were causing user-visible jank in traces
collected from real user devices.

Test: atest NotificationEntryManagerTest
Test: atest NotifCollectionTest
Test: atest NotificationEntryManagerInflationTest
Test: atest LaunchConversationActivityTest

Bug: 230668198
Change-Id: I737a5d85049e5e016fd2f4ad37285001752f5f95