Remove the seats_available_insufficient flow on the event registration editor. As it's no longer possible to confirm an SO and create draft registration. Indeed the registration state is linked to the sale order state. And a validation error is directly raised if there are not enough seats to confirm the SO. task-3555628 closes odoo/odoo#138743 Related: odoo/upgrade#5279 Signed-off-by: Warnon Aurélien (awa) <awa@odoo.com>