test: use mustCall() in test-http-timeout

PR-URL: nodejs#34996
Reviewed-By: Juan José Arboleda <soyjuanarbol@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>

test/parallel/test-http-timeout.js

@@ -20,17 +20,17 @@
 // USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 'use strict';
-require('../common');
+const common = require('../common');
 
 const http = require('http');
 const Countdown = require('../common/countdown');
+const MAX_COUNT = 11;
 
-const server = http.createServer(function(req, res) {
+const server = http.createServer(common.mustCall(function(req, res) {
   res.writeHead(200, { 'Content-Type': 'text/plain' });
   res.end('OK');
-});
+}, MAX_COUNT));
 
-const MAX_COUNT = 11;
 const agent = new http.Agent({ maxSockets: 1 });
 const countdown = new Countdown(MAX_COUNT, () => server.close());