cloud-infra: Adapt delete-stack script according to deps

cloud-infra: Adapt delete-stack script according to deps

Work to distribute engine dependencies across stacks started.

This change will move dependencies from engine core to stacks,
including openstack client. This requires cloud infra jobs'
delete-stack.sh script to be updated to install openstack clients
without using requirements file since the file will not contain
openstack clients anymore. This is also required to verify changes
coming to engine. Without it, stack deletion fails and change gets -1.

https: //jenkins.nordix.org/job/engine-verify-offline-deploy-test-ubuntu1804-city-cloud-master/50/console
Change-Id: Ic54b1b61047e833e2ee40f9eb860ab43115d73ad