fix: support registries without publish times using minimalAgeGate

[oblador]

What's the problem this PR addresses?

When using registries that don't expose the publish time along with minimalAgeGate setting will result in an error of No candidates found as the filter will silently fail and simply exclude it without first checking if it's excepted.

Closes #6906

How did you fix it?

To address this I changed types to optional and mark candidates without publish time as automatically needing quarantine when minimalAgeGate is set instead of silently failing.

Checklist

• I have read the Contributing Guide.

• I have set the packages that need to be released for my changes to be effective.

• I will check that all automated PR checks pass before the PR gets reviewed.