title: Invalid Host Header when using elasticsearch client
body: <p>When using the elasticsearch client (from the elasticsearch npm version 15.4.1), the AWS elasticsearch service complains about an Invalid Host Header. This happens for every request even though they work.</p>
  
  <p>I double-checked the configuration for initializing the elasticsearch client and the parameter "host" is correctly formed.</p>
  
  <pre><code>let test = require('elasticsearch').Client({
      host: 'search-xxx.us-west-1.es.amazonaws.com',
      connectionClass: require('http-aws-es')
  });
  </code></pre>
  
  <p>I expected to get a clean ElasticsearchRequest without a corresponding InvalidHostHeaderRequests (I can see these logs on the Cluster health dashboard of the Amazon Elasticsearch Service).</p>