base

Fix crashes when removing work profile

This isn't specific to work profile. When multiple user
deletions happen in sequence, a race causes a dying user
to lose permissions prematurely. This fix delays removal of
user state until the user is completely cleaned up and all the
processes have been killed.

Bug: 23178833
Change-Id: I1636bc2022416359a25f19a3f65d113c05289cd3