Add a new field for using a custom registry for Cilium

[jandersen-plaid]

Fixes #15786.

There is a bit more context in the issue, but this adds a Registry field to the CiliumNetworkingSpec so that users can override the image registry used to pull Cilium images.

This copies the method used for similar Networking add ons when specifying a Registry argument in their NetworkingSpec; defaulting to quay.io when the Registry field is empty.

[k8s-ci-robot]

Hi @jandersen-plaid. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[hakman]

/ok-to-test

[hakman]

@jandersen-plaid Please rebase to pass the tests.

[hakman]

Thanks for adding this @jandersen-plaid! 😄

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: hakman

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [hakman]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[hakman]

Sorry, I think you will need to rebase one more time it tests don't pass...

[hakman]

/test all

[hakman]

/lgtm