Until a while ago multatuli.wikimedia.org used to be a SRE test host for a number of tests/tasks that can't be done well in Cloud VPS, e.g. testing custom kernels or tests of lower level changes before they get applied to production. multatuli got repurposed as an auth DNS server and generally speaking it would be good to have not only server for those kind of tests, but to (one running Debian stable and the other running Debian oldstable).
We don't need to buy a new machine for these, a spare server should be perfectly fine. There are also no requirements hardware-wise, the smallest setup available is fine. And they can be in any DC, it's also fine to have one server in eqiad and the other in codfw, e.g.
(These hosts are no sensible candidates for a Ganeti instance, e.g. the tests for the microcode tests for Spectre/Meltdown would not work on a KVM instance).