Posture check: AWS ElastiCache cluster not associated with VPC
Query: ```config from cloud.resource where api.name = 'aws-elasticache-cache-clusters' as X; config from cloud.resource where api.name = 'aws-elasticache-describe-replication-groups' as Y; filter '$.Y.memberClusters contains $.X.cacheClusterId and $.X.cacheClusterStatus equals available and ($.X.cacheSubnetGroupName is empty or $.X.cacheSubnetGroupName does not exist)'; show Y;```