Do cleanup when Stopping users

Mark user 0 as initialized, otherwise it will show up as
uninitialized when viewed from secondary user if never switched to user 0.

Bug: 7301595

Also clean up any users that were in the process of being removed, if device
crashes at a bad time.

Change-Id: Ic16a6c9ccb6a64b7463725f6cc279335a821fcd5