Elevate remote/recents animation priority

If we have another process running a remote animation, we need to
elevate its scheduling priority in order to achieve a smooth
animation. To do that, we set the priority as if it would be the
top app.

Test: go/wm-smoke
Test: Capture trace, open/close apps/recents, inspect priority in
trace.

Change-Id: Ia167eeff95700d86e96e96a984099f1e28040b59
Fixes: 73555925