Remove custom emojis on domain purge (#17210)

app/services/purge_domain_service.rb

@@ -5,6 +5,7 @@ class PurgeDomainService < BaseService
     Account.remote.where(domain: domain).reorder(nil).find_each do |account|
       DeleteAccountService.new.call(account, reserve_username: false, skip_side_effects: true)
     end
+    CustomEmoji.remote.where(domain: domain).reorder(nil).find_each(&:destroy)
     Instance.refresh
   end
 end