DeviceEntryIconViewModel uses isUnlocked flow with a slight delay

To avoid transitioning to the unlocked lock icon during the
LOCKSCREEN/AOD => GONE transition.

We also update deviceEntryInteractor.isUnlocked to use
keyguardInteractor.isKeyguardDismissible since the device
entry interactor should only be used when flexiglass
is enabled.

Test: atest DeviceEntryIconViewModelTest
Test: manually authenticate with UDFPS from LS,
and see there's no flash of the unlocked icon
Fixes: 323212430
Fixes: 322512267
Flag: ACONFIG com.android.systemui.device_entry_udfps_refactor STAGING

Change-Id: Id76c422816d439ab8c24c0a13f694f1db2b91efe