Posture check: GCP PostgreSQL instance database flag cloudsql.enable_pgaudit is not set to on
Query: ```config from cloud.resource where cloud.type = 'gcp' AND api.name = 'gcloud-sql-instances-list' AND json.rule = "databaseVersion contains POSTGRES and (settings.databaseFlags[?(@.name=='cloudsql.enable_pgaudit')] does not exist or settings.databaseFlags[?(@.name=='cloudsql.enable_pgaudit')].value does not equal on)"```