Finish recents if it was not in transition when merging

At a rare timing, the recents transition can be cut by a launching
app. e.g. the initial transition becomes TO_FRONT {app TO_BACK},
which doesn't contain recents itself because it is occluded by
the launching app. And the transition of launching app becomes
OPEN {recents TO_BACK}.

So just cancel the recents animation because recents was closing.
Otherwise the animation will keep a long time because
foundRecentsClosing won't be satisfied due to the the transition info
of recents task is missing when the animation started.

Bug: 314635969
Test: Start a new task and swipe up to enter recents at the same time.
Change-Id: Ic5e028608ac4de18da286916a81506ebd418ff7d