Update lockscreenVisibility when a transition is STARTED.

We miss the first STARTED transition otherwise, since the pairwise startedStepWithPrecedingStep hasn't emitted anything yet.

Bug: 278086361
Test: atest SystemUITests
Flag: com.android.systemui.keyguard_wm_state_refactor
Change-Id: Ic86470ca46296baddad4deba6f56574578850840