Make service monitor scrape interval configurable

[youribonnaffe]

What is missing?

The scrape interval for service monitors created by the operator is hardcoded (https://github.com/k8ssandra/k8ssandra-operator/blob/main/pkg/telemetry/prom_cass_servicemonitor.go#L340) and not configurable. It would be nice to be able to set it to a specific value while defining the K8ssandraCluster.

Environment

• K8ssandra Operator version:

1.8.1 but it is also the case for the latest version

Anything else we need to know?:

The workaround I use so far is to disable Prometheus telemetry and create the service monitors manually.