test: fix timeout not being cleared

PR-URL: #54242
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Jake Yuesong Li <jake.yuesong@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Tierney Cyren <hello@bnb.im>

test/parallel/test-pipe-file-to-http.js

@@ -32,11 +32,10 @@ const filename = tmpdir.resolve('big');
 let count = 0;
 
 const server = http.createServer((req, res) => {
-  let timeoutId;
   assert.strictEqual(req.method, 'POST');
   req.pause();
 
-  setTimeout(() => {
+  const timeoutId = setTimeout(() => {
     req.resume();
   }, 1000);