Handle missing ipv6 boolean in network_data.yaml for Ceph
Handle missing ipv6 boolean in network_data.yaml for Ceph

It's not valid input to exclude the ipv6 boolean when
using IPv6, but when this happens the client fails with
a type error. Handle this situation better and return
a better error message.

Closes-Bug: 1956517
Change-Id: Id99346ac0fc336b306550e71da0f9b746ff83ef1

openstack/python-tripleoclient