test: use common.PORT instead of an extraneous variable

This test is not parallelized and so we can use the test commons PORT
variable.

Refs: nodejs#27565 (comment)

PR-URL: nodejs#27565
Fixes: nodejs#27341
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>

test/internet/test-dgram-connect.js

@@ -5,17 +5,15 @@ const { addresses } = require('../common/internet');
 const assert = require('assert');
 const dgram = require('dgram');
 
-const PORT = 12345;
-
 const client = dgram.createSocket('udp4');
-client.connect(PORT, addresses.INVALID_HOST, common.mustCall((err) => {
+client.connect(common.PORT, addresses.INVALID_HOST, common.mustCall((err) => {
   assert.ok(err.code === 'ENOTFOUND' || err.code === 'EAI_AGAIN');
 
   client.once('error', common.mustCall((err) => {
     assert.ok(err.code === 'ENOTFOUND' || err.code === 'EAI_AGAIN');
     client.once('connect', common.mustCall(() => client.close()));
-    client.connect(PORT);
+    client.connect(common.PORT);
   }));
 
-  client.connect(PORT, addresses.INVALID_HOST);
+  client.connect(common.PORT, addresses.INVALID_HOST);
 }));