Disable firewall rule logging by default

[tpdownes]

At high packet rate, we observe performance impacts when Cloud VPC Firewall logging is enabled. This turns logging off by default but allows the user to enable it with metadata included or excluded.

Blueprint tested with all 3 allowed values for var.firewall_log_config. They can be modified in-place non-destructively:

---
blueprint_name: startup-vm-instance

vars:
  project_id:  ## Set project id here
  deployment_name: testfix
  region: us-east4
  zone: us-east4-c

deployment_groups:
- group: first
  modules:
  - id: network1
    source: modules/network/vpc
    settings:
      firewall_log_config: EXCLUDE_ALL_METADATA
  - id: vm0
    source: modules/compute/vm-instance
    use:
    - network1
    settings:
      name_prefix: vm0
      machine_type: n1-standard-2

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 #