Launch the home task as user.

Since there can be multiple home activites for different users, we
should use the correct userId to launch the home activity. This way wm
can pick the correct activity show in the home task.

Fix: 391455493
Test: manual, repro steps in bug
Flag: EXEMPT Bug fix
Change-Id: Ib5dd469bd4d5a6ec801dde51637e02d3b3a2bdd0