do not arrange monitor if it's disabled (wlroots!4520)

This causes us to send negative values to xdg-configures (e.g a bug in our end)

References: https://gitlab.freedesktop.org/wlroots/wlroots/-/merge_requests/4520
(cherry picked from commit 4043fc3093)

dwl.c

@@ -458,6 +458,10 @@ void
 arrange(Monitor *m)
 {
 	Client *c;
+
+	if (!m->wlr_output->enabled)
+		return;
+
 	wl_list_for_each(c, &clients, link) {
 		if (c->mon == m) {
 			wlr_scene_node_set_enabled(&c->scene->node, VISIBLEON(c, m));