http: simplify drain()

Simplify and slightly optimize draining outgoing http streams. Avoid
extra event listener and inline with rest of the drain logic.

PR-URL: https://github.com/nodejs/node/pull/29081
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

lib/_http_common.js

@@ -31,7 +31,6 @@ const { methods, HTTPParser } =
     internalBinding('http_parser') : internalBinding('http_parser_llhttp');
 
 const FreeList = require('internal/freelist');
-const { ondrain } = require('internal/http');
 const incoming = require('_http_incoming');
 const {
   IncomingMessage,
@@ -201,12 +200,6 @@ function freeParser(parser, req, socket) {
   }
 }
 
-
-function httpSocketSetup(socket) {
-  socket.removeListener('drain', ondrain);
-  socket.on('drain', ondrain);
-}
-
 const tokenRegExp = /^[\^_`a-zA-Z\-0-9!#$%&'*+.|~]+$/;
 /**
  * Verifies that the given val is a valid HTTP token
@@ -253,7 +246,6 @@ module.exports = {
   CRLF: '\r\n',
   debug,
   freeParser,
-  httpSocketSetup,
   methods,
   parsers,
   kIncomingMessage,