test: use arrow functions in test-exception-handler

PR-URL: nodejs#23498
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

test/parallel/test-exception-handler.js

@@ -25,16 +25,16 @@ const assert = require('assert');
 
 const MESSAGE = 'catch me if you can';
 
-process.on('uncaughtException', common.mustCall(function(e) {
+process.on('uncaughtException', common.mustCall((e) => {
   console.log('uncaught exception! 1');
   assert.strictEqual(MESSAGE, e.message);
 }));
 
-process.on('uncaughtException', common.mustCall(function(e) {
+process.on('uncaughtException', common.mustCall((e) => {
   console.log('uncaught exception! 2');
   assert.strictEqual(MESSAGE, e.message);
 }));
 
-setTimeout(function() {
+setTimeout(() => {
   throw new Error(MESSAGE);
 }, 10);