Isolate Notification alpha changes for PRIMARY_BOUNCER->GONE

Previously, all lockscreen and NSSL alpha changes were bundled
together, which works in most cases. However, if the shade is
expanded while unlocking, notification must remain visible,
especially for things like inline replies.

This fixes both flag on/off paths.

Fixes: 325118951
Test: atest PrimaryBouncerToGoneTransitionViewModelTest
Flag: ACONFIG com.android.systemui.migrate_clocks_to_blueprint
TEAMFOOD

Change-Id: Ia9a7b46163108e5ddf7b2998ce50bfba1a00ff42