Disable expanding pip when pip is not visible

Prevents expanding pip when the pip is not visible, such as when exiting
from lockscreen. Will need further investigation of b/365907350 for
issue with app not drawing content, but probably not pip related.

Flag: EXEMPT bugfix
Bug: b/365907350
Test: Manually enter pip then open app from lockscreen notification,
verify app stays in pip.

Change-Id: I497f0d54d978ef8d98f11ce03b294a995b2688ec