New major version of the terraform-google-sql-db/postgresql module

• Removes kubernetes integration. Credentials and connection strings must be synced by using secret-manager.
• Removes default postgresql version. The default version will quickly be outdated, and it is not safe to set a new default version.
• Bumps the required terraform version to allow using optionals in the variable types. This improves the auto-generated documentation.
• Cleans up env specific default logic, and adds support for null variables from optional variables.
• Bump default machine size in non-prd to the same as prd. The previous default machine type for non-prod resulted in a lot of issues and very slow creation and modification times