Fix flickering notifs...

... and leaking animator. The smartspace view animator could be
leaked when going to/from AOD while the clock transition was
running. This left a predraw listener attached forever, and was
most noticeably causing flicker on notifications.

It turns out there's no guarantee that an animator underlying a
transition will end, which left the predraw listener attached.
Using a TransitionListener instead seems to be more reliable.

Fixes: 334528077
Fixes: 332979277
Test: Repeatedly switch between large and small clocks with
and without media. Observe traces to ensure no predraw
listener remains attached.
Flag: N/A

Change-Id: Iac51bdde8de524a8ad95bfd116e2eeb55cd47eeb