cri-o: add variable to configure unsecure pull

[hafe]

By default do not allow "unqualified" (without a registry) images
because it is considered unsecure and subject to mitm attacks.

To enable insecure pull configure for example:

crio_registries:
  - "docker.io"
  - "quay.io"

What type of PR is this?

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/kind api-change
/kind bug
/kind cleanup
/kind design
/kind documentation
/kind failing-test
/kind feature
/kind flake

What this PR does / why we need it:

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Clusters using CRI-O as container runtime and where pulling of unqualified images is used, now needs to explicitly allow this.

[k8s-ci-robot]

Hi @hafe. Thanks for your PR.

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[floryut]

/ok-to-test
/lgtm

[hafe]

/retest

[floryut]

/retest

Tests are underway 👍

[hafe]

Maybe we should go the secure way of having it empty by default and make it configurable? Not backwards compatible but more secure

[hafe]

/retest

[Miouge1]

/approve

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hafe, Miouge1

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[floryut]

/lgtm