Fix face unlock does not work for top app in split screen

ActivityManager#getTask() only returned focus activity if we set
argument as 1, enlarge the max size and check package name and
visibility of running task.

BUG: 228128130
Test: 1. Launch any applications that will show biometric prompt
      2. Enter slpit screen mode before biometric prompt showing
      3. Wait for biometric showing and check the biometric prompt
	 funtionality
Change-Id: Ib49a4dcf0061a0f8a9c53505eee4656a2571f2f7