[IMP] payment: remove unused override

The method action_validate_invoice_payment() has been removed from the base
model but is still overriden in the payment module.
This commit will remove the override.

Task id #2285897

closes odoo/odoo#56278

Signed-off-by: Laurent Smet <smetl@users.noreply.github.com>

addons/payment/models/account_payment.py

@@ -83,11 +83,6 @@ class AccountPayment(models.Model):
 
         return transactions
 
-    def action_validate_invoice_payment(self):
-        res = super(AccountPayment, self).action_validate_invoice_payment()
-        self.mapped('payment_transaction_id').filtered(lambda x: x.state == 'done' and not x.is_processed)._post_process_after_done()
-        return res
-
     def action_post(self):
         # Post the payments "normally" if no transactions are needed.
         # If not, let the acquirer updates the state.