Better dashboard display behavior

* Don't show sidebar if only one language is present
* only add in the default language code if it's not already present

common/djangoapps/student/views.py

@@ -472,7 +472,8 @@ def dashboard(request):
 
     language_options = DarkLangConfig.current().released_languages_list
 
-    language_options.append(settings.LANGUAGE_CODE)
+    if settings.LANGUAGE_CODE not in language_options:
+        language_options.append(settings.LANGUAGE_CODE)
 
     cur_lang_code = UserPreference.get_preference(request.user, LANGUAGE_KEY)
     if cur_lang_code:

lms/templates/dashboard.html

@@ -206,7 +206,9 @@
           </span> <span class="data">${ user.email | h }</span>
         </li>
 
+        %if len(language_options) > 1:
         <%include file='dashboard/_dashboard_info_language.html' />
+        %endif
 
         % if external_auth_map is None or 'shib' not in external_auth_map.external_domain:
         <li class="controls--account">