Fix isOccludedByApp to exclude when occluded by communal (a non-app).

This is how the existing flow works, was just an oversight.

Bug: 278086361
Test: atest OccludingAppDeviceEntryInteractorTest
Flag: com.android.systemui.keyguard_wm_state_refactor
Change-Id: I434b0d9bf91cccfef84597dd61a113c125d84eb6