These servers have been replaced by new Noble servers (nb05, nb06,
nb07). These new servers have managed to build every one of our current
images except for gentoo, openeuler, and openeuler arm64. These three
images weren't building on the old system either.
There is a small amount of concern that removing the old servers without
letting them clean up the database after themselves may orphan some
zookeeper database records. However the current rockylinux-9 images were
both built by nb05 or nb06 and we don't have any old records from nb01
or nb02 remaining so it seems nodepool cleans up after itself properly.
Worst case we can probably do manual database edits.
We also remove the version specifier in the docker-compose.yaml file as
`docker compose` ignores it and emits a warning when it is present. Once
this change lands all of our nodepool builders will use `docker compose`
instead of `docker-compose` making this a safe cleanup.
Change-Id: Iab8d2b6493b78cc3711d64119da2da5d3456a25a
7bb12ad33e