[flexiglass] Moves NSSL an additional px down in QS scene

This fixes the swipe up from the bottom edge that collapses QS back to
gone or lockscreen so that it works again (instead of scrolling NSSL
up).

Bug: 370877754
Test: manually verified that dragging up from the bottom of the display
while on QS correctly closes back to LS or Gone scene
Flag: com.android.systemui.scene_container

Change-Id: I797a476f78df5260c8bd3e5abd685caff7b71d42