As we move to using shade through nodepool, several things can consume
clouds.yaml via os-client-config. ansible openstack modules can also read
the file, as well as python-openstackclient. SO - if we start putting
clouds.yaml files places, then we can opt in to using it instead of
directories full of shell script env vars.
Change-Id: If25ee14f06a4530da4779e062b1ad46238e44f2e