Break direct calls to UserController object in AMS from activity classes (12/n)

Make calls from activity classes go through ActivityManagerInternal
interface to case UserController instead of calling AMS.mUserController
object directly. Note that calls to UserController should not hold the
AMS lock.

Bug: 80414790
Test: Existing tests pass
Change-Id: Ie56f08d10b62d609e9b5e31f45b5f0d6eed3a9d4