Update RemoteTransition wrapper to better match pre-Shell behavior.

Specifically, activity->activity transitions used to be categorized as
apps, whereas now they are categorized as nonApps because they don't
have a task associated with them.

Bug: 320961634
Flag: NA
Test: see videos in b/320963010 for the before/after of an animation that
worked pre-Shell

Change-Id: Ie7b35e4619b1f47d366f98382703e2b6add56a52