[Keycloak-operator] Better operator detection

Right now, the playbook assumes that the keycloak operator is installed if the directory has been pulled https://github.com/CloudVE/cloudman-boot/blob/master/roles/cloudman-boot/tasks/auth.yaml#L11 but occasionally it is possible to have pulled/unarchived the directory while having failed to install the operator.
A better check would be looking for the existence of an operator pod.