server: support cgroupv2
server: support cgroupv2

lookup the correct file when running on a system that uses cgroupsv2.

Signed-off-by: Giuseppe Scrivano <20002b7b24c75512093a71a58285826d5c504fca@redhat.com>

mikebrow/cri-o,kubernetes-incubator/ocid,kubernetes-incubator/cri-o,kubernetes-incubator/ocid,mikebrow/cri-o,nalind/cri-o,nalind/cri-o,kubernetes-incubator/cri-o,mikebrow/cri-o,kubernetes-incubator/cri-o,kubernetes-incubator/cri-o,nalind/cri-o,mikebrow/cri-o,kubernetes-incubator/ocid