Use Private Service Connect to connect to CloudSQL database

[wiktorn]

Use PSC endpoints to access Cloud SQL instance.

Cloud SQL databases do leave some resources running after the instance is removed that prevents removal of PSA range, which then prevents whole cluster recreation.

Removing authorized_networks as they are not supported by Cloud SQL when using PSC.

Submission Checklist

Please take the following actions before submitting this pull request.

• Fork your PR branch from the Toolkit "develop" branch (not main)
• Test all changes with pre-commit in a local branch #
• Confirm that "make tests" passes all tests
• Add or modify unit tests to cover code changes
• Ensure that unit test coverage remains above 80%
• Update all applicable documentation
• Follow Cloud HPC Toolkit Contribution guidelines #