test: fix assert.throws error in test-http-parser

The third argument of `assert.throws()` is a message that is used by the
AssertionError, not the message to check in the thrown error. It appears
that there is an assert.throws() in test-http-parser that expects the
latter behavior. Rewrite the call to check the error message. Even if
this wasn't a mistake, this change results in a more robust check.

PR-URL: https://github.com/nodejs/node/pull/19626


Reviewed-By: Daniel Bevenius <daniel.bevenius@gmail.com>
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>