Bouncer shouldn't be translated when occluded

Only checking if the bouncer should be scrimmed isn't enough
since it might have been initialized for performance reasons,
but is hidden at the bottom of the keyguard.

Change-Id: If92083e2c385d51febe0ec3a5e5d3484476caf81
Fixes: 80101176
Test: atest packages/SystemUI/tests/src/com/android/systemui/statusbar/phone/StatusBarKeyguardViewManagerTest.java
Test: manual