Fix AuthContainerViewTest by properly mocking PackageManager#getPackageInfo

This method returns non-null. To prevernt the test crashing, this adds a
mock.

Bug: 423906168
Test: SystemUiRoboTests:AuthContainerViewTest
Flag: com.android.hardware.input.mouse_to_touch_per_app_compat
Change-Id: Iabfedf6e678b6c56e6714acd01c54adb318c0833