Don't draw QS if not visible

When QS changes visibility state (particularly in the lock screen),
there's a frame where the state of the clipping and the drawing of the
ComposeView are out of sync. In order to address this, as we know that
nothing from QS should show when qs is not visible, just don't draw it.

Test: manual, open/close shade in lockscreen
Test: manual, open split shade
Fixes: 404575233
Flag: com.android.systemui.qs_ui_refactor_compose_fragment
Change-Id: I61566431d02330585e2057b2dcd518ac86e58d7e