replace bash for loop when checking API server SANs

[rptaylor]

What type of PR is this?
/kind cleanup

What this PR does / why we need it:
This is an updated rebased version of #8050, see discussion and motivation there.

Special notes for your reviewer:
It may take about one second longer to run by default (maybe several seconds if there are a lot of SANs?) but even for a small cluster Kubespray takes ~ 30 minutes to run so the effect is only ~ 0.1% - 1%, so the impact would not be significant or even perceptible.

Does this PR introduce a user-facing change?:

Replace bash for loop when checking API server SANs

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/lifecycle stale

[rptaylor]

/remove-lifecycle stale

[k8s-triage-robot]

The Kubernetes project currently lacks enough contributors to adequately respond to all issues and PRs.

This bot triages issues and PRs according to the following rules:

• After 90d of inactivity, lifecycle/stale is applied
• After 30d of inactivity since lifecycle/stale was applied, lifecycle/rotten is applied
• After 30d of inactivity since lifecycle/rotten was applied, the issue is closed

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/lifecycle stale

[rptaylor]

/remove-lifecycle stale

[MrFreezeex]

Hey @rptaylor, to me this looks way nicer. For a few seconds penalty I don't think it's a huge issue performance wise indeed... Could you rebase your PR and possibly fix the issue in the CI though?

[rptaylor]

@MrFreezeex Thanks, I rebased and fixed the lint.

[MrFreezeex]

Thanks :D
/lgtm
/ok-to-test

cc @oomichi @floryut raising awareness on this PR for a review as this might get missed in the future as one of the oldest PR stil around 😅.

[floryut]

@rptaylor With added though to my previous thinking, let's go and merge it.

Might be prettier (and so easier to maintain) in the long run
And you're right, if testing done the performance drop is that low, it doesn't matter that much.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: floryut, rptaylor

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