Fix lockscreen jump-cutting in during screen off.

isKeyguardShowDelayed() only returns true if the screen off
animation is currently playing, but since wakefulness events
are dispatched async, it's possible that we try to handle the
pending lock in onFinishedGoingToSleep() before the screen off
animator actually starts running.

We can instead check whether we're intending to delay the
keyguard show, even if we haven't quite started the animation
yet.

Fixes: 256803842
Test: atest KeyguardViewMediatorTest
Test: atest UnlockedScreenOffAnimationControllerTest
Change-Id: I4fbac5c995d535d1fb962e5663e3d47d8f3bf00f