Remove clip adjustment to fix bottom screen flicker issue.

Add a flicker test to verify animation background is no longer
visible through the transition after the fix.

Test: atest
Bug: 284148123
Change-Id: Iae41b96f097a428c3eae0e827caa026154fccf3d
Merged-In: Iae41b96f097a428c3eae0e827caa026154fccf3d