Remove commenting system. Because:

- Actually using it will result in comments being shadowbanned,
  even those posted from Youtube's interfacs, because your account
  gets downranked since no analytics are present so it looks like a
  bot posting the comment.
- It's been broken for awhile

youtube/templates/comments_page.html

@@ -27,9 +27,6 @@
             </section>
         {% endif %}
 
-        {% if not slim %}
-            {{ comments.comment_posting_box(comment_posting_box_info) }}
-        {% endif %}
 
         {% if not comments_info['is_replies'] %}
             <div class="comment-links">