Call ActivityManager to request activity relaunch

Instead of relaunching activity in-process, ask ActivityManager.
requestActivityRelaunch to relaunch it. It can make the correct
decision when activity needs to be relaunched.

Test: manual - switch between users to trigger ActivityThread.handleApplicationInfoChanged

Bug: 37992833
Bug: 37412579
Change-Id: I662a04e3cd82115a6008cef9308a2cf1038d51e1