Repository: nodejs/node
Pull request: test: improve error output of test-http2-client-promisify-connect-error

I'm getting a quite useless error output on Nix CI, showing there's a failed assertion but not showing the actual assertion error. Using `assert.rejects` should improve it greatly, and also makes the test code more readable.

For reference, the current output is:

```
not ok 1611 parallel/test-http2-client-promisify-connect-error
  ---
  duration_ms: 70.93100
  severity: fail
  exitcode: 1
  stack: |-
    node:internal/process/promises:394
        triggerUncaughtException(err, true /* fromPromise */);
        ^
    
    AssertionError [ERR_ASSERTION]: Expected values to be strictly equal:
    + actual - expected
    
    + 'ERR_ASSERTION'
    - 'ECONNREFUSED'
    
        at /build/node-v22.14.0/test/parallel/test-http2-client-promisify-connect-error.js:21:16
        at /build/node-v22.14.0/test/common/index.js:435:15
        at process.processTicksAndRejections (node:internal/process/task_queues:105:5) {
      generatedMessage: true,
      code: 'ERR_ASSERTION',
      actual: 'ERR_ASSERTION',
      expected: 'ECONNREFUSED',
      operator: 'strictEqual'
    }
    
    Node.js v22.14.0
```

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Changed files:
filename: test/parallel/test-http2-client-promisify-connect-error.js
patch: @@ -12,13 +12,10 @@ const server = http2.createServer();
 
 server.listen(0, common.mustCall(() => {
   const port = server.address().port;
-  server.close(() => {
+  server.close(common.mustCall(() => {
     const connect = util.promisify(http2.connect);
-    connect(`http://localhost:${port}`)
-      .then(common.mustNotCall('Promise should not be resolved'))
-      .catch(common.mustCall((err) => {
-        assert(err instanceof Error);
-        assert.strictEqual(err.code, 'ECONNREFUSED');
-      }));
-  });
+    assert.rejects(connect(`http://localhost:${port}`), {
+      code: 'ECONNREFUSED'
+    }).then(common.mustCall());
+  }));
 }));