Use refcounts to manage lifetime of AChoreographer*.

This is more robust then existing new/delete.  In particular, current
code has a leak in AChoreographer_create in case initialize() is not
successful.

Bug: 393217449
Test: presubmit
Flag: EXEMPT_refactor
Change-Id: Ib3d84ee58d953a332b14fd852b53b3507defe74f