Posture check: GCP VM instance serial port output logging is enabled
Query: ```config from cloud.resource where cloud.type = 'gcp' AND api.name = 'gcloud-compute-instances-list' AND json.rule = (status equals RUNNING and name does not start with "gke-") and metadata.items[?any(key contains "serial-port-logging-enable" and value equals "true")] exists```