Fallback to cgroup v1 filesystem if cgroup2 is not supported on the
system so that the test can work also on older kernels without cgroup2
support (e.g. on RHEL-8).
I added another commit to disable cgroupfs_label on kernels that don't have the fix. It is not directly related to this PR, so let me know if you prefer to have it in a separate PR.
Fallback to cgroup v1 filesystem if cgroup2 is not supported on the system so that the test can work also on older kernels without cgroup2 support (e.g. on RHEL-8).