'"Port allocation errors" panel in cgnat report not stats

This stats is not reported properly into grafana. When the stats are increased on the router, there are still reported to be zero on grafana.

Looking the code: https://github.com/6WIND/supervision-grafana/blob/master/tools/resources/panels/next/cgnat-port-alloc-errors.json#L39, it seems that the query request is a copy/paste from cgnat-invalid-packets.json.