Update TripleO Cloud API endpoint for Nodepool

* .../nodepool.yaml.erb: The TripleO Cloud resources for Nodepool
have moved to a new environment, with a different API endpoint. Use
it. Depends on Neutron support from:

    https://review.openstack.org/66394

Change-Id: Ie6af97a71e59f12fa0c6891b1826e61137bc1b8e
Merge "Update TripleO Cloud API endpoint for Nodepool"