test: refactor test-http-agent-timeout-option

Fix flakyness caused by usage of a non-routable IP address.

Refs: #25488 (comment)

test/parallel/test-http-agent-timeout-option.js

@@ -1,23 +1,29 @@
 'use strict';
 
 const { expectsError, mustCall } = require('../common');
-const { Agent, get } = require('http');
+const { Agent, get, createServer } = require('http');
 
 // Test that the `'timeout'` event is emitted on the `ClientRequest` instance
 // when the socket timeout set via the `timeout` option of the `Agent` expires.
 
-const request = get({
-  agent: new Agent({ timeout: 500 }),
-  // Non-routable IP address to prevent the connection from being established.
-  host: '192.0.2.1'
-});
-
-request.on('error', expectsError({
-  type: Error,
-  code: 'ECONNRESET',
-  message: 'socket hang up'
+const server = createServer(mustCall(() => {
+  // Never respond.
 }));
 
-request.on('timeout', mustCall(() => {
-  request.abort();
-}));
+server.listen(() => {
+  const request = get({
+    agent: new Agent({ timeout: 500 }),
+    port: server.address().port
+  });
+
+  request.on('error', expectsError({
+    type: Error,
+    code: 'ECONNRESET',
+    message: 'socket hang up'
+  }));
+
+  request.on('timeout', mustCall(() => {
+    request.abort();
+    server.close();
+  }));
+});