This commit adds two types of cross repository jobs: python unit test and
npm test. The initial commit covers the following plugins as non-voting jobs.
They can be used as templates if more projects are tested as cross jobs.
* manila-ui for python unit test
* ironic-ui for npm test
Note that ironic-ui python unit test has only one test which checks
the panel is registered expectedly, so I don't think we need to cover
ironic-ui as a cross python unit test job.
We sometimes create gate check changes but periodic jobs can do
most of them, particularly in stable branhces.
This commit is planed to backport to stable branches.
Note that we already have periodic-stable-jobs (for pyXX and docs jobs)
but it is nice to have npm and integration jobs in this coverage.
Once it is available in stable branches, I will configure the Grafana
dashboard to monitor healthiness in stable branches.