Upload container images to Github Container Registry

@juliusvonkohout

As @juliusvonkohout mentioned in kubeflow/manifests#3010, DockerHub will introduce more restricted container image limitations for anonymous users.

So, it would also be better to push all container images to GHCR for bertter UX.

Note: This does not indicate removing images from DockerHub and stopping the push to DockerHub. Both should be maintained.

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