CGroups v2

[jasonschroeder-sfdc]

Buildfarm is using cgroups v1 paths to create groups for executions.

Everything (operating systems with systemd etc, as well as k8s) seems to have moved on to cgroups v2.

Open questions:

• does BuildFarm need cgroups v1 AND cgroups v2 support concurrently? Or can buildfarm jump forward to v2?

[werkt]

We need both as a migration path. An installation maintainer should be able to throw a single config flag (ideally outside of buildfarm), and have it just work equivalently.

Detection of version support should be the mode of discovery, and both impls should function equivalently until we decide at a later change to deprecate v1