test: move require('http2') after crypto check

This test currently fails when configured --without-ssl:
Error [ERR_NO_CRYPTO]:
Node.js is not compiled with OpenSSL crypto support

This commit moves the require of http2 to come after the crypto check to
avoid the error.

PR-URL: #19907
Reviewed-By: Richard Lau <riclau@uk.ibm.com>
Reviewed-By: Trivikram Kamat <trivikr.dev@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: danbev

test/parallel/test-http2-client-write-empty-string.js

@@ -1,11 +1,11 @@
 'use strict';
 
 const assert = require('assert');
-const http2 = require('http2');
 const common = require('../common');
 if (!common.hasCrypto)
   common.skip('missing crypto');
 
+const http2 = require('http2');
 
 for (const chunkSequence of [
   [ '' ],