Disable notification shade close animation when occluded.

This is causing a flicker when an activity opens over keyguard. The
keyguard is occluded by the activity, so we shouldn't animate behind the
occlusion.

Bug: 242860396
Test: manually on device when opening showWhenLocked activity over the
keyguard

Change-Id: Ie57a69815bf7a9460b0f90408010535eb9b9e172