Do JS fix for collectstatic that we had on main for discussion's index.html

lms/templates/discussion/single_thread.html

@@ -10,6 +10,7 @@
 
 <%block name="js_extra">
 <%include file="_js_body_dependencies.html" />
+<%static:js group='discussion'/>
 </%block>
 
 <%include file="../courseware/course_navigation.html" args="active_page='discussion'" />