Add mpi4py test suite to Jenkins builds

[bwbarrett]

Per https://github.com/open-mpi/ompi/issues/4126, we want to add the mpi4py tests to the Jenkins builds. They are designed to run single node, and run in a couple minutes, so a single test should still finish before the make check test.

[zerothi]

@dalcinl @jsquyres @ggouaillardet sorry for pinging you. I think this could be immensely useful to not only debug OpenMPI but also downstream libraries which ompi now relies more and more on.

I have now for several years been installing software and I always find some corner-case problems in my ompi-installations which are first found in the mpi4py tests. As @dalcinl said in https://github.com/open-mpi/ompi/issues/4126#issuecomment-324069429, most problems are not due to mpi4py.
I think having the mpi4py test-suite lined up against this would be hugely beneficial, it is just so much simpler to have more tests in python and a closer collaboration between the python test-suite and the mpi-developers (not only openmpi) would be beneficial to all users.

Is there anything the community can do to speed up this process? Hints and guidelines for adding such things would be helpful.

[dalcinl]

Is this ever going to happen? Or Am I supposed to keep opening issues over and over again when broken things get merged into main?