design: Fix missing rendered_markdown class on /me content.

There may be a deeper issue that various JavaScript logic expects
every message to have a `.message_content` element, but we definitely
should have the `.rendered_markdown` class on any markdown content.

Fixes #13634.

static/templates/me_message.hbs

@@ -9,7 +9,7 @@
         <i class="zulip-icon bot" aria-label="{{t 'Bot' }}"></i>
         {{/if}}
 
-        <span class="status-message auto-select">
+        <span class="rendered_markdown status-message auto-select">
             {{{ status_message }}}
         </span>