In order to reduce the packages required to pip install
on to the hosts, we allow the service setup to be delegated
to a specific host, defaulting to the deploy host.
1. We no longer need tempest_requires_pip_packages,
so it is removed.
2. The openstack_openrc role is executed in the playbook,
so we do not need it as a meta-dep any more.
3. All uses of our custom keystone module have been
replaced with standard Ansible modules.
4. Using the service delegation model, it makes no sense
to run the resource creation on all hosts, so we
use run_once instead.
5. Given that we're using developer mode for master
integrated builds, and pip.conf is present, we need
to use the CLI to create the virtualenv so that we
can use the '--never-download' option.
Change-Id: I572db645b64a4a0ac6255bc36eaac1be13336989
81f6bda4c0