DEV: Reduce duplication (#26329)

app/models/category_list.rb

@@ -207,22 +207,7 @@ class CategoryList
       @categories.delete_if { |c| to_delete.include?(c) }
     end
 
-    allowed_topic_create = Set.new(Category.topic_create_allowed(@guardian).pluck(:id))
-
-    parent_ids =
-      Category
-        .secured(@guardian)
-        .where(parent_category_id: categories_with_descendants.map(&:id))
-        .pluck("DISTINCT parent_category_id")
-        .to_set
-
-    categories_with_descendants.each do |category|
-      category.notification_level = notification_levels[category.id] || default_notification_level
-      category.permission = CategoryGroup.permission_types[:full] if allowed_topic_create.include?(
-        category.id,
-      )
-      category.has_children = parent_ids.include?(category.id)
-    end
+    Category.preload_user_fields!(@guardian, categories_with_descendants)
   end
 
   def prune_empty