Fixing sample cluster integration with multi-user.

Launching the activity on the current user, while keeping the renderer
service under user 0. Switching activity-service communication to use a
messenger rather than local binding.

Bug: 79884417
Test: Manual on device
Change-Id: I36d922d3cd422cde48fa7e6f7ebe2eeb82f059df
(cherry picked from commit 2bac68cba3d32fc17020d4710ed3ebb1d0e96739)
5 files changed