qa_devstack: Enable specific Neutron extensions
qa_devstack: Enable specific Neutron extensions

Currently not all extensions can be tested with Devstack. vpnaas needs
openswan which isn't available for openSUSE.

gosipyan/automation,gosipyan/automation,SUSE-Cloud/automation,gosipyan/automation,vmoravec/automation,aspiers/automation,aspiers/automation,aspiers/automation,vmoravec/automation,SUSE-Cloud/automation,gosipyan/automation,SUSE-Cloud/automation,aspiers/automation,SUSE-Cloud/automation,vmoravec/automation,vmoravec/automation