This PR updates the containerd driver to support changes in how Nomad
manages cgroups when running on a machine using cgroups.v2
- The namespace is now set to "nomad.slice", which containerd uses as
the cgroup parent.
- The container name is re-oriented to the new naming convention,
i.e. "<allocID>.<taskName>.scope". This is necessary for Nomad to
be able to manage the cpuset resource.
d8c2c2fad2