[prometheus-operator] grafana servicemonitor label is hardcoded to "grafana"

[Morriz]

this prevents multiple grafana instances deployed with this chart to not have their own servicemonitor....

[scottrigby]

🚧 This chart is now deprecated.

Further development has moved to prometheus-community/helm-charts. The chart has been renamed kube-prometheus-stack to more clearly reflect that it installs the kube-prometheus project stack, within which Prometheus Operator is only one component.

If applicable, please re-open this issue there. Thanks!