Add some more logging for why a change might not be passed to Launcher

- The bug report in b/324435197 indicates that we are starting a recents
  transition, but the app going TO_BACK is not being passed to launcher.
  This CL adds a bit more logging to see if the task is incorrectly
  being considered as a non-leaf task, or something else.

Bug: 324435197
Test: Just adding logging
Change-Id: I9f692a49950cc859f0f7227b79c8e4c6ddbfeeb0