Update k8s registry references

[asa3311]

Ⅰ. Describe what this PR does

Per kubernetes/k8s.io#4780, Kubernetes is migrating its image registry to registry.k8s.io, and this repository is impacted.

We have to update the references of k8s.gcr.io to registry.k8s.io by April 3rd to remain up-to-date.

Here's a quick search for k8s.gcr.io on this repo. [search result]. Note that there may be other valid references (like, in the form of generated code, etc) which we have to be aware of.

Ⅱ. Does this pull request fix one issue?

Ⅲ. Special notes for reviews

[kruise-bot]

Welcome @asa3311! It looks like this is your first PR to openkruise/rollouts 🎉

[codecov-commenter]

Codecov Report

Merging #126 (b5617bb) into master (2b48eba) will not change coverage.
The diff coverage is n/a.

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@@           Coverage Diff           @@
##           master     #126   +/-   ##
=======================================
  Coverage   44.66%   44.66%           
=======================================
  Files          47       47           
  Lines        4865     4865           
=======================================
  Hits         2173     2173           
  Misses       2335     2335           
  Partials      357      357           

Flag	Coverage Δ
unittests	44.66% <ø> (ø)

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[veophi]

/lgtm

[furykerry]

/approve

[kruise-bot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: furykerry, liangyuanpeng

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