[FIX] test_mail: please bring back our send method !

A patched method was not unpatched. Which triggered issues in a staging
master branch trying to untie a bit mail tests.

closes odoo/odoo#40046

Signed-off-by: Xavier Dollé (xdo) <xdo@odoo.com>

addons/test_mail/tests/test_mail_mail.py

@@ -97,6 +97,8 @@ class TestMailRace(common.TransactionCase, mail_common.MockEmails):
         self.assertEqual(notif.notification_status, 'sent')
 
         # some cleaning since we commited the cr
+        self.env['ir.mail_server']._revert_method('send_email')
+
         notif.unlink()
         message.unlink()
         mail.unlink()