Update analytics tracking ID

The company managing site analytics for docs.openstack.org has
requested we update the tracking script snippet it uses. This
switches the existing implementation to the new version they
provided to the OpenInfra Foundation staff.

A similar change I91104f6f0f287e09379f89ccf3a2b084fdde9465 covers
the copy of this in the openstackdocstheme repo.

Change-Id: I201161a51ce4483c7bad4e16fbfb39493c4ca712

www/templates/google_analytics.tmpl

@@ -1,11 +1,8 @@
-<!-- Google Analytics -->
-<script>
-(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
-(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
-m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
-})(window,document,'script','//www.google-analytics.com/analytics.js','ga');
-
-ga('create', 'UA-17511903-1', 'auto');
-ga('send', 'pageview');
+<!-- Google tag (gtag.js) -->
+<script async src="https://www.googletagmanager.com/gtag/js?id=G-DD299CMF7V">
+</script>
+<script>
+window.dataLayer = window.dataLayer || [];
+function gtag(){dataLayer.push(arguments);} gtag('js', new Date());
+gtag('config', 'G-DD299CMF7V');
 </script>
-<!-- End Google Analytics -->

www/templates/script_search.tmpl

@@ -6,7 +6,7 @@
                     language: 'en'
                 });
                 var _gaq = _gaq ||[];
-                _gaq.push([ "_setAccount", "UA-17511903-1"]);
+                _gaq.push([ "_setAccount", "G-DD299CMF7V"]);
                 function _trackQuery(control, searcher, query) {
                     var gaQueryParamName = "q";
                     var loc = document.location;