fix function NodeAllocatableRoot

[mysunshine92]

What type of PR is this?

Uncomment only one /kind <> line, hit enter to put that in a new line, and remove leading whitespace from that line:

/kind bug
/kind cleanup

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #88969

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

if we set parameter cgroupPerQos=false and cgroupRoot=/docker，this function will retrun  nodeAllocatableRoot=/docker/kubepods, it is not right, the correct return should be /docker.
cm.NodeAllocatableRoot(s.CgroupRoot, s.CgroupDriver)

kubeDeps.CAdvisorInterface, err = cadvisor.New(imageFsInfoProvider, s.RootDirectory, cgroupRoots, cadvisor.UsingLegacyCadvisorStats(s.ContainerRuntime, s.RemoteRuntimeEndpoint))
the above funtion，as we use cgroupRoots to create cadvisor interface，the wrong parameter cgroupRoots will lead eviction manager not  to collect metric from /docker, then kubelet frequently print those error：
E0303 17:25:03.436781 63839 summary_sys_containers.go:47] Failed to get system container stats for "/docker": failed to get cgroup stats for "/docker": failed to get container info for "/docker": unknown container "/docker"
E0303 17:25:03.436809 63839 helpers.go:680] eviction manager: failed to construct signal: "allocatableMemory.available" error: system container "pods" not found in metrics

Additional documentation e.g., KEPs (Kubernetes Enhancement Proposals), usage docs, etc.:

[mattjmcnaughton]

Thanks for your pr :)

Could you please include, either in your commit message or pr description (or ideally both), a description of the fix that you're making? Having the description makes it a lot easier for a reviewer the pr makes the intended change :)

[mysunshine92]

ping @dashpole

[mysunshine92]

/test pull-kubernetes-e2e-gce

[dashpole]

you will have to change this function in other builds as well.

[dashpole]

Good find. This lgtm after the cross-builds are fixed.

[mysunshine92]

Good find. This lgtm after the cross-builds are fixed.

I can not understand "cross-builds are fixed.", would you like to explain it for me ?
thanks @dashpole

[mysunshine92]

/test pull-kubernetes-e2e-gce-100-performance

[mysunshine92]

ping @dashpole

[mysunshine92]

ping @mattjmcnaughton

[wangyx1992]

/test pull-kubernetes-typecheck

[mysunshine92]

ping @mattjmcnaughton ,please add to lgtm and approved,thanks

[dashpole]

The type-check test is essentially a lightweight cross-build. I.E. make sure this builds for "other" systems.

/lgtm
/approve

[mattjmcnaughton]

ping @mattjmcnaughton ,please add to lgtm and approved,thanks

You need sign off from one of the owners, which I'm not :)
/assign @yujuhong

[dashpole]

/priority important-soon

[mysunshine92]

The type-check test is essentially a lightweight cross-build. I.E. make sure this builds for "other" systems.

thanks for your explanation, i have modified it.

[mysunshine92]

ping @yujuhong ,please add approved label，thanks

[mysunshine92]

ping @yujuhong

[mysunshine92]

ping @yujuhong @Random-Liu @vishh ,please add approved label，thanks

[mysunshine92]

ping @yujuhong @Random-Liu @vishh ,please add approved label，thanks

[yujuhong]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: dashpole, mysunshine92, yujuhong

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