[RONs-AOD] Use Notification Panel margins

RONs AOD takes all available width without any margin in split shade. With this CL, it is going to use same horizontal margins as notification panel is using.

Bug: 402146241
Test: Post a RON on foldable. Transition the unfolded device to AOD and see the RON Skeleton
Flag: android.app.ui_rich_ongoing
Change-Id: I9f3f684a074f9ccc9386d3e72352137f75784f4b