Force set to entered state to avoid overflow

Force set the PiP transition state to ENTERED_PIP
before recursively calling exitPip() while ENTERING_PIP
in an attempt to start exiting PiP
(e.g. due to onActivityRestartAttempt).

This should help avoid potential stack overflow errors.

Bug: 345686267
Test: direct enter PiP and tap to expand quickly
Change-Id: Ie0ad45f2ff1892257e4c95e211e5dd5b4826d5f6