fix: Automatically remove expired story mention (#5300)

When a user mentions the connected Instagram page in a story, the story's content is downloaded in Chatwoot, then if the user deletes the story, the content persists in the platform.

fixes: #5258

spec/factories/channel/instagram_channel.rb

@@ -6,5 +6,9 @@ FactoryBot.define do
     user_access_token { SecureRandom.uuid }
     page_id { SecureRandom.uuid }
     account
+
+    before :create do |_channel|
+      WebMock::API.stub_request(:post, 'https://graph.facebook.com/v3.2/me/subscribed_apps')
+    end
   end
 end