Better handle interruptions when shared element is disabled

This CL improves the interruption logic to add support for *disabled*
shared element transitions.

See b/290930950#comment23 for before/after videos.

Bug: 290930950
Test: ElementTest
Flag: com.android.systemui.scene_container
Change-Id: I18830d775bd6315e44cf037091bce3e8da7c5973