Add small delay to animate device entry unlock icon

We don't want to flash the unlock icon when the
user has unlocked the device and the device is
transitioning to GONE.

This is the easiest solution until keyguard transitions
and unlocked states are better coordinated and potentially
ordered.

Test: manually confirmed (10/10 times) unlock icon doesn't show
when authenticating with UDFPS
Test: manually confirmed non-bypass face auth still updates UI
to the unlocked icon as expected (and doesn't feel delayed)
Test: atest UdfpsAccessibilityOverlayViewModelTest
Fixes: 322512267
Flag: ACONFIG com.android.systemui.device_entry_udfps_refactor DEVELOPMENT
Change-Id: Icf11ded912563838b729711d554611ce01faf2da

Change-Id: I912bf8bbc26d85f58822fde0db83fecbafd544a3