Avoid collecting transient activity in next transition

The moveFocusableActivityToTop always collects the activity
even if there is no order change. If the next transition is
started to collect, the transient activity may be a participant
that makes inTransition() return true to disturb some conditions.

In normal case, RecentsTransitionHandler already calls setFocusedTask
to make sure the transient activity is on top with focus. So at
finishTransition, assume it should already on top then only need to
set focus if it was not focused.

Bug: 276707493
Test: Swipe auto-pip from fullscreen landscape to portrait.
      PiP should not disappear.
Change-Id: I1cd2859279d6760189fda7060c5e194ce3a1e060