http: remove legacy parser

Remove the legacy `http_parser` implementation as a dependency
and all code that uses it in favor of llhttp, given that the latter
has been the default for all of Node 12 with no outstanding issues.

PR-URL: https://github.com/nodejs/node/pull/29589


Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Jiawen Geng <technicalcute@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Minwoo Jung <minwoo@nodesource.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>