test: changed function to arrow function

Convert callback functions that are anonymous
to arrow functions for better readability.
Also adjusted the `this` object in places where
that was required.
PR-URL: #32875
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

Author: nimit95

test/parallel/test-net-after-close.js

@@ -24,14 +24,14 @@ const common = require('../common');
 constassert=require('assert');
 constnet=require('net');
 
-constserver=net.createServer(common.mustCall(function(s){
+constserver=net.createServer(common.mustCall((s)=>{
 console.error('SERVER: got connection');
 s.end();
 }));
 
-server.listen(0,common.mustCall(function(){
-constc=net.createConnection(this.address().port);
-c.on('close',common.mustCall(function(){
+server.listen(0,common.mustCall(()=>{
+constc=net.createConnection(server.address().port);
+c.on('close',common.mustCall(()=>{
 console.error('connection closed');
 assert.strictEqual(c._handle,null);
 // Calling functions / accessing properties of a closed socket should not