For helm installs, make monitoring stack opt-in

[psschwei]

What is the expected enhancement?

Most users running Kubernetes clusters will already have a monitoring solution in place for their existing clusters (whether that's a managed service from a cloud provider or their own custom Prometheus etc.). As such, our Prometheus / Grafana / Loki installs will be redundant in a majority of cases. As a result, we should set the default option in our helm chart to opt-in (i.e. disabled by default) for those components.