Clean up elapsed_realitime and expandable_public flags

Cleans up:
1. android.app.notif_entry_creation_time_use_elapsed_realtime
2. android.app.expanding_public_view

Test: atest NotificationEntryTest VisualStabilityCoordinatorTest
Fixes: 417549185
Fixes: 409611920
Flag: EXEMPT flag cleanup
Change-Id: Idc78499578cc58d6c5bc1fc23fa47584682e2465