Fixed an issue where opaque huns would clip the following notifs

Previously HUNs appearing on top of other huns would clip them
mostly away. Now they are excluded if they are opaque since
overlaps don't have to be ensured there.

Fixes: 422658515
Test: atest SystemUITests
Flag: com.android.systemui.physical_notification_movement
Change-Id: Idf4f2d90fd57d0245fdd7e6d7a15a2adc08050a4