Prevent UnlockAnimationController from dismissing keyguard...

... on exit animation cancel. When the animators are canceled,
they will still call exitKeyguardAndFinishSurfaceBehindRemoteAnimation()
which can then continue to dismiss the keyguard even though it
decided to just relock. Short circuit this call.

Seems to happen during a race condition with SIM PIN/PUK screens.

Fixes: 370748717
Test: atest KeyguardViewMediatorTest
Flag: com.android.systemui.relock_with_power_button_immediately
Change-Id: I42a0aaa221ed2120ad2cf8b2a4ab88c4685f692b