Flexiglass: don't log misleading status bar state error

We don't actually set `StatusBarStateController.upcomingState` when
Flexi is enabled, so don't log an error based on the value of
`upcomingState`.

Bug: 359530769
Test: manual, enable flexi and navigate around
Flag: com.android.systemui.scene_container
Change-Id: Iac5ef348ee37f6d0db23eee805f5ebefb54ffd8d