Ensure lockscreen alpha of 0f on fast swipes to bouncer

If the system is very bogged down, or if the user swipes very fast
to go to the bouncer, it can essentially bypass most or all of
the manual transition steps and go straight to FINISHED.

Ensure keyguard alpha is 0f at this time.

Also, ignore all shade expansion information when transitioning
from LOCKSCREEN. This results in greatly simpler logic for when
to consume shade information.

Test: atest KeyguardRootViewModelTest
Test: atest LockscreenToPrimaryBouncerTransitionViewModelTest
Bug: 398738793
Flag: EXEMPT bugfix
Change-Id: I174e444541e207efed7c9a595f001eaaf8a609b2