Make handleSwipePipToHome config-at-end invariant

Currently PipTransition#handleSwipePipToHomeTransition()
doesn't have any fallback for a case where Core did not
actually mark a PiP activity as defer-config-at-end.

 - How can we get into such edge case?
This can happen in rare cases where, for instance,
the PiP candidate activity is marked as isVisibleRequested=false
by Core during setConfigAtEnd().

 - How are we fixing this edge case with this CL?
We are making the handleSwipePipToHomeTransition() subroutine
handling the jumpcut animation for TRANSIT_PIP in swipe-to-pip
config-at-end activity agnostic.
More specifically, we can still handle the jumpcut animation
with PiP task as the only change available to us after startAnimation().
Effectively, we are making swipe-pip-to-home handling more robust.

Bug: 433791839
Flag: EXEMPT bugfix
Test: manually swipe-to-pip and fold the device during animation
Change-Id: I6aa4b6cae62700bb6a9f384456a0c4b55c36e10d