Use keyguard transitions to ensure correct scrim

Listen for both ALTERNATE_BOUNCER->GONE and PRIMARY_BOUNCER->GONE
transitions, and animate existing notification and behind scrim
values. This will correct an issue where the scrim disappears when
tapping on a notification in the expanded shade.

Bug: 295326104
Test: PrimaryBouncerToGoneTransitionViewModelTest
BouncerToGoneFlowsTest

Change-Id: I03207db36b780b21a6e4d2ea5c87234b7f8ea0c1