Move the animation delay for credential UI up one layer

This way we can remove the view and do the appropriate logic that's
supposed to happen in onDetachedFromWindow.

Fixes: 143174046

Test: atest com.android.systemui.biometrics
Test: BiometricPromptDemo, tap "Use password", repeat 10+ times
Change-Id: Idd1f2b2bc91fae97d97f7301ee762ed946da9f8f