Fix alarms launching while on the hub

This handles a race condition between the dreaming signal and the
occlusion signal, similar to FromDreamingTransitionInteractor.

Fixes: 359094748
Test: atest KeyguardTransitionScenariosTest
Test: starting alarm while idle on the hub
Flag: com.android.systemui.communal_scene_ktf_refactor
Change-Id: Iec6d86a26eee505a946334bb83022e31c48b2e89