Revert "http: reset parser.incoming when server response is finished"

This reverts commit 779a05d.

PR-URL: #29263
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

lib/_http_server.js

@@ -621,8 +621,6 @@ function resOnFinish(req, res, socket, state, server) {
   assert(state.incoming.length === 0 || state.incoming[0] === req);
 
   state.incoming.shift();
-  // Reset the .incoming property so that the request object can be gc'ed.
-  if (socket.parser) socket.parser.incoming = null;
 
   // If the user never called req.read(), and didn't pipe() or
   // .resume() or .on('data'), then we call req._dump() so that the