Nitpicky, but we've used a lot of random spacings and names in the past,
but we're trying to be completely consistent on "cgroup vN" now.
Generated by `fd -0 | xargs -0 -n1 sed -ri --follow-symlinks 's/cgroups? ?v?([0-9])/cgroup v\1/gI'`.
I manually ignored places where it's not appropriate to replace (eg.
"cgroup2" fstype and in src/shared/linux).
This test runs on the unified hierarchy, and ensures that cgroup
delegation works properly, i.e. writ access is granted and the requested
controllers are enabled.