This switches the ubuntu-jammy, ubuntu-noble, and
debian-bullseye nodesets from nodepool to niz.
It also adds non-niz-prefixed versions of all the
niz nodesets so that we can start to use the new
names.
Change-Id: I9bfa3c305d23a75ea492cfffeef9d3f80d0d1c60
5d404f4921