test: refactor test-httpparser.response.js

* replace CRLF constant with '\r\n' literal
* fix typo in HTTP header name

PR-URL: nodejs#14290
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Gibson Fahnestock <gibfahn@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Refael Ackermann <refack@gmail.com>

test/async-hooks/test-httpparser.response.js

@@ -9,7 +9,6 @@ const { checkInvocations } = require('./hook-checks');
 const binding = process.binding('http_parser');
 const HTTPParser = binding.HTTPParser;
 
-const CRLF = '\r\n';
 const RESPONSE = HTTPParser.RESPONSE;
 const kOnHeadersComplete = HTTPParser.kOnHeadersComplete | 0;
 const kOnBody = HTTPParser.kOnBody | 0;
@@ -19,10 +18,10 @@ const hooks = initHooks();
 hooks.enable();
 
 const request = Buffer.from(
-  'HTTP/1.1 200 OK' + CRLF +
-  'Content-types: text/plain' + CRLF +
-  'Content-Length: 4' + CRLF +
-  CRLF +
+  'HTTP/1.1 200 OK\r\n' +
+  'Content-Type: text/plain\r\n' +
+  'Content-Length: 4\r\n' +
+  '\r\n' +
   'pong'
 );