Remove references to deprecated methods

Removes usage of deprecated methods in CommunalSceneStartable and
CommunalViewModel, as there is now a standalone interactor for
scene-related logic.

Test: atest SystemUiRoboTests
Flag: com.android.systemui.glanceable_hub
Bug: 331591373
Change-Id: I75097a1fc9be9aae5164a7ccb5fa5d3469c49a77