add no_subcategories query param in url only if its true (#7439)

app/controllers/list_controller.rb

@@ -382,7 +382,9 @@ class ListController < ApplicationController
 
     # hacky columns get special handling
     options[:topic_ids] = param_to_integer_list(:topic_ids)
-    options[:no_subcategories] = options[:no_subcategories] == 'true'
+    if options[:no_subcategories] == 'true'
+      options[:no_subcategories] = true
+    end
 
     options
   end