Avoid many-to-many join by collapsing records by claim using max-by

Signed-off-by: Phillip Schichtel <phillip@schich.tel>

deploy/charts/rules/volume/volume-rules.json

@@ -9,7 +9,7 @@
                   "description": "Persistent Volume Claim '{{ $labels.persistentvolumeclaim }}' has no consumer",
                   "summary": "Persistent Volume Claim '{{ $labels.persistentvolumeclaim }}' in namespace '{{ $labels.namespace }}' is not consumed by any pod in any namespace"
                },
-               "expr": "kube_persistentvolumeclaim_info unless (kube_persistentvolumeclaim_info * on(persistentvolumeclaim) group_left kube_pod_spec_volumes_persistentvolumeclaims_info) == 1",
+               "expr": "kube_persistentvolumeclaim_info unless (kube_persistentvolumeclaim_info * on(persistentvolumeclaim) group_left (max by (persistentvolumeclaim) (kube_pod_spec_volumes_persistentvolumeclaims_info)))) == 1",
                "for": "5m",
                "labels": {
                   "severity": "info"