wlr_scene: Don't damage whole damage ring when exiting direct scanout

Direct scanout damage will just accumulate on the damage ring while in
direct scanout and properly damage when we exit anyway. On the flip side
since we now manage backend damage submission ourselves, this won't break
that either.

types/scene/wlr_scene.c

@@ -1719,10 +1719,6 @@ bool wlr_scene_output_build_state(struct wlr_scene_output *scene_output,
 		scene_output->prev_scanout = scanout;
 		wlr_log(WLR_DEBUG, "Direct scan-out %s",
 			scanout ? "enabled" : "disabled");
-		if (!scanout) {
-			// When exiting direct scan-out, damage everything
-			wlr_damage_ring_add_whole(&scene_output->damage_ring);
-		}
 	}
 
 	if (scanout) {