We were using `--no-test-exit-error` for upgrade tests but weren't
actually checking for test failures after.
Instead of running kola directly, just use the `fcosKola` custom step
which automatically takes care of e.g. running tests in parallel and
archiving results.
Move the alternative builds into the Jenkinsfile.
Update it to do a FCOS build + kola run.
We drop the flatpak/rpm-ostree runs for now; the former
will needs some work to do the automatic virt bits. The
latter I think we can circle back to when we e.g. figure
out how to include rpm-ostree's tests in kola runs.
Jonathan Lebon
Colin Walters