Disabled the template_history endpoint

- Removed the code for the template_history endpoint and replaced with a
redirect to the new page so that anyone is forwarded on
- Updated the template to point to the new template_usage page

app/templates/views/dashboard/dashboard.html

@@ -40,7 +40,7 @@
     {% if partials['has_template_statistics'] %}
       {{ ajax_block(partials, updates_url, 'template-statistics') }}
       {{ show_more(
-        url_for('.template_history', service_id=current_service.id),
+        url_for('.template_usage', service_id=current_service.id),
         'See templates used by month'
       ) }}
     {% endif %}