Improve the getCgroupSubsystemsV1() which uses random record per subsystem
returned by libcontainercgroups.GetCgroupMounts().
Example array from GetCgroupMounts():
```
[
{
Mountpoint: "/sys/fs/cgroup/systemd",
Root: "/",
Subsystems: []string len: 1, cap: 1, ["systemd"],},
{
Mountpoint: "/sys/fs/cgroup/cpu,cpuacct",
Root: "/",
Subsystems: []string len: 2, cap: 2, ["cpu","cpuacct"],},
{
Mountpoint: "/sys/fs/cgroup/systemd/some/path",
Root: "/some/path",
Subsystems: []string len: 1, cap: 1, ["systemd"],},
]
```
becames a map:
```
[
"memory": "/sys/fs/cgroup/memory/kubepods",
"systemd": "/sys/fs/cgroup/systemd/some/path",
]
```
which seems to be wrong.
Using shortest path of mountpoint per subsystem would be more reliable.
reference issue: https://github.com/kubernetes/kubernetes/issues/95488
de60340e51