feat: Remove subscription on WhatsApp inbox delete (#11977)

- remove webhook subscription while deleting a whatsapp inbox created
via embedded signup

Co-authored-by: Muhsin Keloth <muhsinkeramam@gmail.com>

app/models/channel/whatsapp.rb

@@ -34,6 +34,7 @@ class Channel::Whatsapp < ApplicationRecord
 
   after_create :sync_templates
   after_create_commit :setup_webhooks
+  before_destroy :teardown_webhooks
 
   def name
     'Whatsapp'
@@ -105,4 +106,8 @@ class Channel::Whatsapp < ApplicationRecord
     # Don't raise the error to prevent channel creation from failing
     # Webhooks can be retried later
   end
+
+  def teardown_webhooks
+    Whatsapp::WebhookTeardownService.new(self).perform
+  end
 end