test: replace anonymous closure function with arrow function

PR-URL: #24435
Reviewed-By: Michaël Zasso <[email protected]>
Reviewed-By: Colin Ihrig <[email protected]>
Reviewed-By: Gireesh Punathil <[email protected]>
Reviewed-By: Trivikram Kamat <[email protected]>
Reviewed-By: Ouyang Yadong <[email protected]>
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Sakthipriyan Vairamani <[email protected]>

test/parallel/test-dgram-send-callback-recursive.js

@@ -29,7 +29,7 @@ client.on('listening', function() {
   onsend();
 });
 
-client.on('message', function(buf, info) {
+client.on('message', (buf, info) => {
   received++;
   if (received === limit) {
     client.close();