This migrates the passthrough code to using the
openstacksdk instead.
This should also have the added benefit of improving
the security posture of this dashboard.
There is a bug in openstacksdk for Designate floating IPs
which will be solved in [1], for now we workaround that
so that older versions of openstacksdk is supported.
This also fixes the 6 year old bug of supporting pagination
for the designate dashboard.
[1] https://review.opendev.org/c/openstack/openstacksdk/+/903879
Closes-Bug: 1729261
Change-Id: Id5ebdc5849d46dc10ab864a54afe37eb9c8f71b7
caa257dafc