Flexiglass: use Interactor for device public logic in LS user manager

When Flexi is enabled, use DeviceUnlockedStatus.isUnlocked to decide if
the device is public (i.e. not unlocked), instead of
KeyguardStateController and StatusBarStateController.

Bug: 359530769
Test: presubmit
Flag: com.android.systemui.scene_container
Change-Id: Ie7ec69ae8966e56590d06e5fc2d0a1fc706e110b