Make USER_REMOVED an ordered broadcast and send it before the user's
state is completely removed from the system. This gives services the
opportunity to clean up their state, while still having access to the
user's directory and UserInfo object (such as serial number).
Tell SyncManager to skip over dying/partially created users.
Improve UserManager tests, waiting for users to be removed fully.
Bug: 7382252
Change-Id: I93cfb39c9efe6f15087bf83c569a2d154ef27168
db6a14cc85