reorganize var defaults

[KubeKyrie]

What type of PR is this?
/kind flake

What this PR does / why we need it:
reorganize var defaults, and have a default value defined only once
Which issue(s) this PR fixes:

#11822

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

Reorganize variable defaults

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: KubeKyrie
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[k8s-ci-robot]

Hi @KubeKyrie. Thanks for your PR.

I'm waiting for a kubernetes-sigs 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.

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[VannTen]

Unless this is taking care of all the instances ( I don't think so ? ) please remove the `fixes` to avoid auto closing the issue. Also, I don't think we should have null checksum, we should rather figure out how to obtain the correct ones. /ok-to-test