Add testinfra 3rd party testing
Add testinfra 3rd party testing

Run the system-config-run-base-ansible-devel test against testinfra
pull requests.  This test installs ansible and testinfra from upstream
and then runs our base playbooks, giving a good smoke-test of any big
issues.

Discussed with upstream @

 https://github.com/philpep/testinfra/pull/436#issuecomment-489784345

Depends-On: https://review.opendev.org/656908
Change-Id: Ifc763ba54bff9be4aabd6ac1ce176140648e209e

openstack-infra/project-config,openstack-infra/project-config