[IMP] avoid sending mail for validation transactions

Before this commit, validation transactions would send an email when the
token is assigned to the order.

closes odoo/odoo#155167

Taskid: 3675875
X-original-commit: f70967e240058d8a6b095fc58c591249e517bd31
Signed-off-by: Arnaud Joset (arj) <arj@odoo.com>

addons/sale/models/payment_transaction.py

@@ -53,6 +53,8 @@ class PaymentTransaction(models.Model):
                 for so in tx.sale_order_ids:
                     so.reference = tx._compute_sale_order_reference(so)
 
+            if tx.operation == 'validation':
+                continue
             # Send the payment status email.
             # The transactions are manually cached while in a sudoed environment to prevent an
             # AccessError: In some circumstances, sending the mail would generate the report assets