[RON] Fix LargeIcon alignment for RONs

Since there is no expander, notification topline view grows to the end of its parent. So it's drawn close or under the large icon depending on the notification header content.
This CL adds expand button spacer which takes up as much space as minimal expander so that notification topline view layouts correctly.

Bug: 393369727
Test: Screenshot tests (for existing UI) && screenshots for large icon will come after
Flag: com.android.systemui.ui_rich_ongoing_force_expanded
Change-Id: Ic75b26ec59d7d1f61db2a41d8165850bc1571bd0