Fix owned account notes not being deleted when an account is deleted (#16579)

* Add account_notes relationship

* Add tests

* Fix owned account notes not being deleted when an account is deleted

* Add post-migration to clean up orphaned account notes

app/models/concerns/account_interactions.rb

@@ -81,6 +81,9 @@ module AccountInteractions
     has_many :following, -> { order('follows.id desc') }, through: :active_relationships,  source: :target_account
     has_many :followers, -> { order('follows.id desc') }, through: :passive_relationships, source: :account
 
+    # Account notes
+    has_many :account_notes, dependent: :destroy
+
     # Block relationships
     has_many :block_relationships, class_name: 'Block', foreign_key: 'account_id', dependent: :destroy
     has_many :blocking, -> { order('blocks.id desc') }, through: :block_relationships, source: :target_account

app/services/delete_account_service.rb

@@ -4,6 +4,7 @@ class DeleteAccountService < BaseService
   include Payloadable
 
   ASSOCIATIONS_ON_SUSPEND = %w(
+    account_notes
     account_pins
     active_relationships
     aliases
@@ -34,6 +35,7 @@ class DeleteAccountService < BaseService
   # by foreign keys, making them safe to delete without loading
   # into memory
   ASSOCIATIONS_WITHOUT_SIDE_EFFECTS = %w(
+    account_notes
     account_pins
     aliases
     conversation_mutes