At the moment we don't have control what version of rally-openstack
is being installed. So we are installing latest version available in
PyPi. However rally package version is defined in
rally-openstack constraints.
With this patch we add variables to be able to adjust source of
rally-openstack as well as pick version for installation.
We also temporary disable upgrade jobs to resolve circular dependency
Needed-By: https://review.opendev.org/c/openstack/openstack-ansible/+/847272
Change-Id: I8100dfd3544c0530815fb877b44b960d404f635b
136dfa02d0