Weakly hold callback reference from OnPredrawListener

Weakly holding the required predraw references prevents leaking the
transition and all captured views if the PredrawListener is not
correctly cleaned up.

Bug: 414596090
Flag: NONE Bugfix
Test: Manually checked clock switch animation in several scenarios
Change-Id: Ibe64caff6648034da2ab9558edabc54d2eb9274a