test: remove string literal message from assertion

Remove string literal from assert.strictEqual message to improve output
of AssertionError.

Backport-PR-URL: #22912
PR-URL: #22849
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

test/parallel/test-http-information-processing.js

@@ -36,8 +36,8 @@ server.listen(0, function() {
  });
 
  req.on('response', function(res) {
- assert.strictEqual(countdown.remaining, 1,
-  'Full response received before all 102 Processing');
+ // Check that all 102 Processing received before full response received.
+ assert.strictEqual(countdown.remaining, 1);
  assert.strictEqual(200, res.statusCode,
  `Final status code was ${res.statusCode}, not 200.`);
  res.setEncoding('utf8');