sphinxmark is no longer compatible with the latest release of Sphinx
which is causing all of our documentation jobs to fail. This patch
removes it as our current usage of openstacktheme for documentation
already provides watermarks for current branch and notices for which
branch the documentation covers.
With addition of pip_install on every node, we don't
need to have pip_install as a meta dependency.
This patch implements an initial set of jobs intended to match
the current job execution method. It does not intend to improve
how the jobs are executed - only to replicate what is currently
in openstack-infra/openstack-zuul-jobs and provide the platform
to iterate on.