Clear Rails cache for destroyed comment's ancestors and destroy buffer_updates for articles (#3065)

* Touch all ancestors before destroying comment

* Destroy buffer_updates when article is destroyed

app/models/article.rb

@@ -22,7 +22,7 @@ class Article < ApplicationRecord
   counter_culture :organization
 
   has_many :comments, as: :commentable, inverse_of: :commentable
-  has_many :buffer_updates
+  has_many :buffer_updates, dependent: :destroy
   has_many :notifications, as: :notifiable, inverse_of: :notifiable
   has_many :rating_votes
   has_many :page_views

app/models/comment.rb

@@ -251,6 +251,7 @@ class Comment < ApplicationRecord
 
   def before_destroy_actions
     commentable.touch(:last_comment_at) if commentable.respond_to?(:last_comment_at)
+    ancestors.update_all(updated_at: Time.current)
     remove_notifications
     bust_cache_without_delay
     remove_algolia_index