Move Istio Grafana Dashboards from Monitoring to Istio-Controlplane Package

Similar to the process tackled in issue #1243 (closed) Migrate the JSON Dashboard templates from the Monitoring package to the istio-controlplane package.

The JSON files can be moved to chart/dashboards/ within the istio-controlplane package, and a ConfigMap similar to this but pointing to the correct resources/files will need to be created at chart/templates/bigbang/. See these recent additions to loki & anchore-enterprise.

• JSON Dashboards moved to istio-controlplane package
• ConfigMap to create JSON templates in istio-controlplane package
• templates removed from monitoring package (chart/dashboards/istio/ folder & chart/templates/bigbang/dashboards/istio-dashboards.yaml removed)
• BigBang MR with both package updates included, Monitoring + Istio HRs are healthy and Istio dashboards are present in Grafana