Renumber sandbox1-b-eqiad IPv6 to match convention

We've split sandbox VLANs into separate /56 per datacenter. Move our
only existing IPv6 sandbox VLAN into the new space. This is especially
good timing, as dickson.freenode.net is offline and ripe-atlas-eqiad is
not yet online.

Change-Id: I2ccfcb53b020886a3b5b28ef0a249e8cc77e6ee0
Allocate IPv4/IPv6 for RIPE Atlas codfw/ulsfo

These two go in the sandbox VLANs, similar to how eqiad is set up.

Change-Id: I870e548c0e3cbceb84ccc9b6e88d5a89faaf1bbc