Use the IPv6 documentation prefix as the default cidr
Use the IPv6 documentation prefix as the default cidr

Don't use a cidr which might be routable, instead use the
IPv6 documentation prefix which should be dropped and
filtered by routers according to RFC 3849.

Change-Id: I5efc30ca633118a5fb517dace77aaffb49fd2013

cisco-openstack/tempest,openstack/tempest,openstack/tempest,cisco-openstack/tempest