Replace/Consume Istio's Prometheus/Grafana by existing Prometheus-operator
Followed this guide https://medium.com/@emirmujic/collect-cluster-and-istio-metrics-with-prometheus-operator-42d4499d621a and it worked out for me on Istio 1.2.2:
https://medium.com/@emirmujic/collect-cluster-and-istio-metrics-with-prometheus-operator-42d4499d621a