Fix the blank PiP window when unlock

When the keyguard is showing or animating with the surfaces behind,
there is no need for PiP to be shown or offset-by-shelf-height.

Video: http://recall/-/aaaaaabFQoRHlzixHdtY/g6b3BQS2iH7TibwA9eqq1x
Bug: 230638352
Test: follow the reproduce step, see video
Change-Id: Ia4264a8cac2b34a2f7e9b85b35ebee7f74842aa8