Simplify method to render admin menu

The `side_menu` helper method isn't necessary since commit 13b3d9cebc.

app/helpers/admin_helper.rb

@@ -1,12 +1,4 @@
 module AdminHelper
-  def side_menu
-    if namespace == "moderation/budgets"
-      render "/moderation/menu"
-    else
-      render "/#{namespace}/menu"
-    end
-  end
-
   def namespaced_root_path
     "/#{namespace}"
   end

app/views/layouts/admin.html.erb

@@ -13,7 +13,7 @@
       <%= check_box_tag :show_menu, nil, false, role: "switch" %>
 
       <nav id="side_menu" class="admin-sidebar">
-        <%= side_menu %>
+        <%= render "/#{namespace}/menu" %>
       </nav>
 
       <div class="admin-content">