Revert "Fix notification group dismissal fade animation"

This reverts commit 01397a78.

Reason for revert: Apparently, this change made the SystemServerTiming_PhaseActivityManagerReady-mean test time increase by 12.7%. Therefore, I want to revert it until I figure out, what is causing this increase.

Bug: 253532643

Change-Id: I347c865ab791ba1fc20bf03a34d9a8f2a5ce60ce