Add time measurement logs to UserLifecycleTests broadcast receivers.

This CL also introduces BroadcastWaiter.runThenWaitForBroadcasts
method to make sure possible previous broadcasts are ignored.
Also UserSwitchWaiter helper class is added to reduce code
duplication, along with some code refactoring.

Bug: 200217686
Test: atest MultiUserPerfTests:android.multiuser.UserLifecycleTests --no-bazel-mode
Change-Id: I34fb07194fe946c61ae89a936a6bbf4d5de77025