Post encryption notification after attempting to unlock profiles

Currently this notification is posted when the parent user is in
RUNNING_UNLOCKING state, before tied profiles are unlocked. As a
result, this notification is briefly visible even in cases when
the profile is about to be unlocked automatically. Given that it
is a high importance notification it results in a baloon.
With this change it only attempts to post the notification after
unlocking the profiles, and bails out because user key is already
unlocked in storage manager.

Test: manual, booting up with unified/separate work challenge.
Test: manual, booting up without device lock (only profile lock).
Test: manual, triggering work mode in various configurations.
Test: atest frameworks/base/services/tests/servicestests/src/com/android/server/locksettings/
Bug: 132945758
Change-Id: Iab9b48d03e94bd1bf0e89cbfc94ece742077bba0