desktop/output: Clear modeset timer on output manager apply

If a modeset timer exists at the time we apply an output manager config,
clear it to avoid a useless double commit.

(cherry picked from commit 6334597)

Author: kennylevinsen

sway/desktop/output.c

@@ -657,6 +657,10 @@ static void output_manager_apply(struct sway_server *server,
 done:
 	if (ok) {
 		wlr_output_configuration_v1_send_succeeded(cfg);
+		if (server->delayed_modeset != NULL) {
+			wl_event_source_remove(server->delayed_modeset);
+			server->delayed_modeset = NULL;
+		}
 	} else {
 		wlr_output_configuration_v1_send_failed(cfg);
 	}