Replace k8s.gcr.io with registry.k8s.io

[xmudrii]

What type of PR is this?

/kind cleanup

What this PR does / why we need it:

This PR replaces all k8s.gcr.io references with registry.k8s.io. See the linked issue for more details.

Which issue(s) this PR fixes: xref https://github.com/kubernetes/k8s.io/issues/4738

Release note:

Replace all `k8s.gcr.io` references with `registry.k8s.io`

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[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: astoycos, xmudrii

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Needs approval from an approver in each of these files: - ~~[cmd/cyclonus/OWNERS](https://github.com/kubernetes-sigs/network-policy-api/blob/master/cmd/cyclonus/OWNERS)~~ [astoycos] Approvers can indicate their approval by writing `/approve` in a comment Approvers can cancel approval by writing `/approve cancel` in a comment