http: free the parser before emitting 'upgrade'

Ensure that the parser is freed before emitting the 'connect' or
'upgrade' event.

PR-URL: https://github.com/nodejs/node/pull/18209


Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Jon Moss <me@jonathanmoss.me>
Reviewed-By: Fedor Indutny <fedor.indutny@gmail.com>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>