Hierarchy controller(HNC) can't be disabled in KCC

[ziyue-101]

Checklist

• I did not find a related open enhancement request.
• I understand that enhancement requests filed in the GitHub repository are by default low priority.
• If this request is time-sensitive, I have submitted a corresponding issue with GCP support.

Describe the feature or resource

HNC is disabled by setting the hnc.enabled GCP API field to false. However, by setting the KCC's spec.hnc.enabled field to false doesn't set the underlying GCP API to false. This means users can't disable HNC through KCC properly. We should consider to have the behavior of setting false to a boolean in the KRM equivalent to setting false on the underlying GCP API.

Additional information

Even though users can attempt to disable HNC through Gcloud, KCC reconciliation will revert the change back.

Importance

No response