test: fix flaky keepalive timeout test on slow platforms

Author: Han5991

test/sequential/test-http-server-keep-alive-timeout-slow-client-headers.js

@@ -5,12 +5,13 @@ const assert = require('assert');
 const http = require('http');
 const net = require('net');
 
-const server = http.createServer(common.mustCall((req, res) => {
+const server = http.createServer({
+  keepAliveTimeout: common.platformTimeout(100),
+  keepAliveTimeoutBuffer: common.platformTimeout(1000),
+}, common.mustCall((req, res) => {
   res.end();
 }, 2));
 
-server.keepAliveTimeout = common.platformTimeout(100);
-
 server.listen(0, common.mustCall(() => {
   const port = server.address().port;
   const socket = net.connect({ port }, common.mustCall(() => {