test: update test to comply with lint rule

Ref: https://github.com/nodejs/node/pull/19502#issuecomment-378450321

PR-URL: https://github.com/nodejs/node/pull/19784
Reviewed-By: Teddy Katz <teddy.katz@gmail.com>
Reviewed-By: Matheus Marchini <matheus@sthima.com>

test/parallel/test-https-host-headers.js

@@ -104,7 +104,7 @@ function testHttps() {
       path: `/${counter++}`,
       host: 'localhost',
       setHost: true,
-      //agent: false,
+      // agent: false,
       port: this.address().port,
       rejectUnauthorized: false
     }, cb).on('error', thrower).end();