Remove xmpp.net provider info. Service has been discontinued

src/templates/registration_form.html

 <p class="provider-title">{{{domain}}}</p>
-<a href='https://xmpp.net/result.php?domain={{{domain}}}&amp;type=client'>
-    <img class="provider-score" src='https://xmpp.net/badge.php?domain={{{domain}}}' alt='xmpp.net score' />
-</a>
 <p class="title">{{{title}}}</p>
 <p class="instructions">{{{instructions}}}</p>