fix: provide a sensible example for a privateca Root CA example

[hoexter]

This one looks a lot like someone copied by accident the subordinate example out of certificate_authority_subordinate/main.tf as a root CA. Thus it contains a lot of values set which are outright invalid or not recommend for Root CA certficates if you consider RFC 5280 and CA/B Baseline Requirements as the standard to follow.

Also the subordinate example is a bit odd, e.g. configuring SAN on any kind of CA certificate doesn't make sense. And the resources examples there make use of the same pool name.

I tried to keep the lifetime setting, but set it to 99 years. That is probably a sensible value for a P(rivate)KI setup. For something public 10y or 15y are probably more sensible.

Description

Fixes #630

Note: If you are not associated with Google, open an issue for discussion before submitting a pull request.

Checklist

Readiness

• [] Yes, merge this PR after it is approved
• [X] No, don't merge this PR after it is approved

Testing

• [ ] I have performed tests described in the Contributing guide:

  • [ ] Tests pass: terraform apply
  • [x] Lint pass: terraform fmt check

--> this should get a test run somewhere, right now I don't have a test setup at hand to validate it against the API of the CAS

[msampathkumar]

/gcbrun

[Sita04]

@msampathkumar Can you help add @pmansour to the list of reviewers?

[msampathkumar]

This PR has been inactive for two months. If this inactivity continues for another two weeks, I will close the request.

[hoexter]

@msampathkumar I updated the PR long ago with the proposed changes by @pmansour. Thus it's just waiting for a review by you/your team. :)

[glasnt]

/gcbrun