Set a return url when confirming setup intent in test scenario

A return URL is now required if the payment methods do not disable it.

Closes #12509

modules/account_payment_stripe/tests/scenario_account_payment_stripe_intent.rst

@@ -89,6 +89,7 @@ Register card::
     ...         })
     >>> setup_intent = stripe.SetupIntent.confirm(
     ...     customer.stripe_setup_intent_id,
+    ...     return_url='http://localhost/',
     ...     payment_method=payment_method)
     >>> cron_update_intent, = Cron.find([
     ...     ('method', '=', 'account.payment.stripe.customer|stripe_intent_update'),