promoter: validate docker_login
promoter: validate docker_login

Implements workaround for docker_login bug which returns success even
when authentication fails.

https://github.com/ansible/ansible/issues/32868

Includes note os we will be able to remove the workaround once we
get the ansible module fixed.

Change-Id: I875181cf6fca8ee99f822db16eae1a65cdeb74cb

redhat-openstack/rdo-infra,rdo-infra/ci-config,redhat-openstack/rdo-infra,redhat-openstack/rdo-infra,rdo-infra/ci-config,rdo-infra/ci-config,redhat-openstack/rdo-infra,rdo-infra/ci-config