[FIX] payment_*: tests when running with a non-default port

For payment_buckaroo and payment_sips (at least) running with a
non-standard port is an issue to the `test_redirect_form_value` tests:
while the form and test will use respectively the base_url and the
configuration port, both check a response signature which is
predicated upon a base url of `http://127.0.0.1:8069`.

This means the test does not pass when run with a different port, and
may not pass if the database was installed with a different port
either (because this may have caused the `web.base_url` to be set to
the installation port).

The other payment modules don't seem to have such signature
verification and thus apparently don't mind running with non-default
port.

Update in 15.2: `test_webhook_notification_confirms_transaction` also
broke but differently, because the payment utils would fetch (and use)
the `web.base.url` they get confused if a db is installed using one
port then the tests are run using an other (or something along those
lines), despite `HttpCase` trying to set the `web.base.url` (could be
an ordering thing).

Anyway a working solution seems to be to *remove* the bespoke code
from `PaymentTestUtils` and fix `HttpCase.base_url()` so it uses the
right port (apparently that'd never been fixed). This does require
adapting the patch being forward-ported as `base_url` is now a
callable, not an attribute.

Also re-remove the attractive nuisance of the odoo.tests.common.PORT
constant which does not work: it is evaluated before the configuration
has been loaded and is thus always set to the default (8069).

closes odoo/odoo#86068

X-original-commit: c28c99f7399da91e1a6176d6f97d4fc947013cae
Signed-off-by: Xavier Morel (xmo) <xmo@odoo.com>

addons/payment_sips/tests/test_sips.py

@@ -45,6 +45,9 @@ class SipsTest(SipsCommon, PaymentHttpCommon):
             "Payulatam: transaction reference wasn't correctly singularized.")
 
     def test_redirect_form_values(self):
+        self.patch(self, 'base_url', lambda: 'http://127.0.0.1:8069')
+        self.patch(type(self.env['base']), 'get_base_url', lambda _: 'http://127.0.0.1:8069')
+
         tx = self.create_transaction(flow="redirect")
 
         with mute_logger('odoo.addons.payment.models.payment_transaction'):