Modify occluded for shade window take#2

Oops, use transitionValue instead. isFinishedIn will not
change until the next FINISHED state emits. Rather, we
only need to care about when the user is idle in this
state.

This will count GLANCEABLE_HUB as an occluded state,
and not change the value when transitioning between
occluded states.

Fixes: 359939084
Test: atest NotificationShadeWindowModelTest
Flag: com.android.systemui.use_transitions_for_keyguard_occluded
Change-Id: I49070394a75620ecbf3638674419c319e4e4eb48