test: reduce the number of requests and parsers

The maximum number of parsers in the free list is set to 1000. However
the test does not need to use this maximum. Reduce it to 50.

Refs: nodejs/node#50228 (comment)
PR-URL: nodejs/node#50240
Fixes: nodejs/node#49564
Reviewed-By: Yagiz Nizipli <yagiz@nizipli.com>
Reviewed-By: Vinícius Lourenço Claro Cardoso <contact@viniciusl.com.br>

Author: lpinca

test/sequential/test-http-regr-gh-2928.js

@@ -8,6 +8,8 @@ const httpCommon = require('_http_common');
 const { HTTPParser } = require('_http_common');
 const net = require('net');
 
+httpCommon.parsers.max = 50;
+
 const COUNT = httpCommon.parsers.max + 1;
 
 const parsers = new Array(COUNT);