Fix AnimatorListeners.forEndCallback()

Override onAnimationEnd(Animator), rather than (Animator, boolean)
which may not be called.

Test: Swipe right to quick switch from home, then swipe back left
(in the same gesture), ensure next quick switch isn't broken.
Bug: 185554764

Change-Id: I53e7526ed5b55fbae9aa654ace70a6ef7561e1d8