Update KeyguardMonitor when UnlockMethod changes

If UnlockMethodChanges but StatusBarState does not, KeyguardMonitor was
not updated. This happened when user changed and may have made
KeyguardMonitor believe it was not secure.

Test: manual: Create another user and and have "Add users on lock
screen" off. Switch from secondary to owner without going out of
KEYGUARD
Fixes: 134447252

Change-Id: Id39bf876d6e573002965d0aa14fd6e54c323aba9