AOD transitions to GONE (not LS) if security is NONE

If the keyguard is dismissible, then AOD should transition
to GONE, not the LOCKSCREEN.

Test: Set security setting to NONE and enable AOD. Observe
the KeyguardTransitionRepository log goes from AOD => GONE
when the power button is pressed on AOD.
Bug: 335673842
Flag: None

Change-Id: Ief92ac2d376705b559206a0266ae92a27192144e