ipa[server,replica,client]: Deactivate Python2/3 test

This test is not properly working with EL-8 nodes as the default system
python is not located in /usr/bin. Additionally Ansible 2.8 is able to
detect the default python version on the system. As the installation
base for IPA 4.5.90 where the Python 3 bindings have not been working
properly should be really small or not existing any more the deactivation
of this test should be fine.