test: remove common.PORT from test-net-write-callbacks.js

Switch test-net-write-callbacks.js from common.PORT to a port assigned
by the operating system.

PR-URL: nodejs#31839
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Yongsheng Zhang <zyszys98@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Shelley Vohr <codebytere@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>

Author: Trott

test/pummel/test-net-write-callbacks.js

@@ -20,7 +20,7 @@
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 'use strict';
-const common = require('../common');
+require('../common');
 const net = require('net');
 const assert = require('assert');
 
@@ -55,8 +55,8 @@ function makeCallback(c) {
   };
 }
 
-server.listen(common.PORT, function() {
-  const client = net.createConnection(common.PORT);
+server.listen(0, function() {
+  const client = net.createConnection(server.address().port);
 
   client.on('connect', function() {
     for (let i = 0; i < N; i++) {