[BUG] Koordlet does not support custom cgroup root

[j4ckstraw]

What happened:
when deploy koordinator in kind cluster, koordlet crashbackoff with such error:

I0604 08:06:27.263217   10115 states_pods.go:128] pod informer started
E0604 08:06:27.263309   10115 pleg.go:150] failed to watch path /host-cgroup/kubepods.slice, err inotify_add_watch /host-cgroup/kubepods.slice: no such file or directory
F0604 08:06:27.263342   10115 states_pods.go:124] Unable to run the pleg: inotify_add_watch /host-cgroup/kubepods.slice: no such file or directory

What you expected to happen:
koordinator ADAPTS to configurations other than cgroup-root=/

How to reproduce it (as minimally and precisely as possible):

kind create cluster 
install koordinator according to https://koordinator.sh/docs/installation

Anything else we need to know?:
with cgroupRoot=/kubelet, ExpandSlice will expand /kubelet/kubepods/besteffort/ to /kubelet.slice/kubelet-kubepods.slice/kubelet-kubepods-besteffort.slice/

refer kubernetes-sigs/kind#3947 (comment)

Environment:

[saintube]

Yes. The Koordlet does not fully support a custom cgroup root of the Kubelet. Currently, to start the Koordlet in KinD, please set the Kubelet CgroupRoot to /.
Example: https://github.com/koordinator-sh/koordinator/blob/main/test/kind-conf.yaml

[saintube]

link #2303