[flexiglass] Fix issue where wallpaper wasn't showing when exiting AOD

It's a long story, I'll attempt it here:
1. As part of the KTF-Flexiglass integration, in ag/28051313, we shut
   down the code in FromAodTransitionInteractor by changing
   TransitionInteractor.maybeHandleInsecurePowerGesture to return true
   when Flexiglass is on
2. This meant that the KTF transition from AOD to LOCKSCREEN isn't
   happening when Flexiglass is on
3. That in turn meant that the light reveal animation code doesn't kick
   in
4. In NotificationShadeWindowControllerImpl.applyKeyguardFlags, the code
   checks the light reveal state. Specifically it checks
   lightRevealScrimOpaque which is always true in AOD but becomes false
   in LOCKSCREEN and, because that transition wasn't happening, the
   flag SHOW_WALLPAPER was never set by that code

The CL changes the return from true to false which still cuts out the
side-effect in TransitionInteractor but lets the side-effect in
FromAodTransitionInteractor occur, allowing the light reveal to run and
fixing the bug.

Fix: 352405139
Test: manually verified that the bug is fixed: the wallpaper is re-shown
when waking up from AOD and still hidden when entering AOD
Test: manually tested this with auth method None and auth method Swipe.
Both seem to behave properly but there are two new bugs that I'm filing
separately. One bug is that switching between None and Swipe is not
actually listened to by System UI. The other bug seems more related to
this fix is a wallpaper visibility flicker that occurs when locking the
device from the launcher: it seems like the wallpaper gets hidden and
shown multiple times in quick succession.
Flag: com.android.systemui.scene_container

Change-Id: I7ae08a8d9d1b43a2bbb61ff316db018e6756cb9a