Backport of Don't allow setting dead server last contact threshold to less than 1 minute into release/1.12.x

[hc-github-team-secure-vault-core]

Backport

This PR is auto-generated from #22040 to be assessed for backporting due to the inclusion of the label backport/1.12.x.

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Warning automatic cherry-pick of commits failed. If the first commit failed,
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The person who merged in the original PR is:
@raskchanky
This person should manually cherry-pick the original PR into a new backport PR,
and close this one when the manual backport PR is merged in.

merge conflict error: POST https://api.github.com/repos/hashicorp/vault/merges: 409 Merge conflict []

The below text is copied from the body of the original PR.

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This is a frequent source of problems when people tune their autopilot configs. I took a quick pass over the other autopilot config values and didn't see any that screamed for validation quite as much as this one, but if there are others that people think should be validated for some valid range of values, I'm happy to add those.

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Overview of commits

• d407078

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[raskchanky]

I'll do this one manually

[github-actions]

CI Results:
All Go tests succeeded! ✅