http: don't cork .end when not needed

PR-URL: #36633
Backport-PR-URL: #36940
Fixes: #36620
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Danielle Adams <adamzdanielle@gmail.com>

lib/_http_outgoing.js

@@ -775,7 +775,8 @@ OutgoingMessage.prototype.end = function end(chunk, encoding, callback) {
     encoding = null;
   }
 
-  if (this.socket) {
+  // Not finished, socket exists and data will be written (chunk or header)
+  if (this.socket && !this.finished && (chunk || !this._header)) {
     this.socket.cork();
   }