kuberuntime: don't override the pod IP for pods using host network

[yujuhong]

This fixes the issue of not passing pod IP via downward API for host network pods.

[k8s-reviewable]

This change is 

[yujuhong]

This fixes #43531

Tested manually.
Writing a unit test for this can be tricky. I'll file an issue for adding a node e2e test.

[Random-Liu]

/lgtm

The logic is too confusing. We should clean this up at some point. :)

[yujuhong]

The logic is too confusing. We should clean this up at some point. :)

I think we can push the responsibility of populating the ip to individual runtime packages (e.g., kuberuntime and rkt).

[dchen1107]

I remembered @freehan fixed this in old dockertool before. :-)

/lgtm

[jayunit100]

So to clarify, the determineSandboxIp is the reason this took so long ?

[k8s-github-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: Random-Liu, dchen1107, yujuhong

Needs approval from an approver in each of these OWNERS Files:

• pkg/kubelet/OWNERS [Random-Liu,dchen1107,yujuhong]

You can indicate your approval by writing /approve in a comment
You can cancel your approval by writing /approve cancel in a comment

[yujuhong]

So to clarify, the determineSandboxIp is the reason this took so long ?

Not sure what you meant. The bug is about not passing the pod ip to the container at creation time as environment variables. You'll still get the correct pod IP in the pod status.

[k8s-github-robot]

Automatic merge from submit-queue (batch tested with PRs 43533, 43539)