Fix Notification animation controller memory leak

This fixes leaking of NotificationLaunchAnimatorController instances (together with their referenced Notification entries) by breaking a dependency cycle through IPC.
Also removes completion callback - it's a very easy avenue to leak even more objects accidentally and is currently unused in SysUI code.

Bug: 299069405
Bug: 298028699
Bug: 293929945
Test: unit tests for attached class. Reproduced issue on cheetah,
confirmed fix of issue with a profiler.

Change-Id: Ib17577cba17ed35b24c4ab32ce0ed55fc7a24605