layouts: Revert to built-in Disqus template

Hugo 0.25 improved the embedded Disqus template so we can just use
theirs now.

See: https://github.com/gohugoio/hugo/pull/3655
See: https://github.com/gohugoio/hugo/pull/3639

layouts/_default/single.html

@@ -83,7 +83,7 @@
   {{ end }}
 
   {{ if and (.Site.DisqusShortname) (ne .Params.comments false) }}
-  {{ partial "disqus.html" . }}
+  {{ template "_internal/disqus.html" . }}
   {{ end }}
   </footer>
   {{ end }}

layouts/partials/disqus.html

@@ -1,19 +0,0 @@
-<div id="disqus_thread"></div>
-<script type="text/javascript">
-
-(function() {
-  // Don't ever inject Disqus on localhost--it creates unwanted
-  // discussions from 'localhost:1313' on your Disqus account...
-  if (window.location.hostname == "localhost")
-    return;
-
-  var dsq = document.createElement('script'); dsq.type = 'text/javascript'; dsq.async = true;
-  var disqus_shortname = '{{ .Site.DisqusShortname }}';
-  dsq.src = '//' + disqus_shortname + '.disqus.com/embed.js';
-  (document.getElementsByTagName('head')[0] || document.getElementsByTagName('body')[0]).appendChild(dsq);
-})();
-</script>
-<noscript>Please enable JavaScript to view the <a href="http://disqus.com/?ref_noscript">comments powered by Disqus.</a></noscript>
-<a href="http://disqus.com/" class="dsq-brlink">comments powered by <span class="logo-disqus">Disqus</span></a>
-
-{{- /* vim: set ts=2 sw=2 et: */}}