Tempest install with upper constraints was bumping openstacksdk in
kolla-ansible venv past the <4.14 pin [1]. Zuul executor
openstack.cloud collection is not working with it, so aarch64 image
task failed with "module 'openstack' has no attribute 'version'".
Separate venv keeps the pin for openstack.cloud and u-c for tempest.
[1] https://review.opendev.org/c/openstack/kolla-ansible/+/994759
Change-Id: I105b845378d6ccdf25355575cf86367a20e53edc
Signed-off-by: Bartosz Bezak <bartosz@stackhpc.com>