Dashboard data source

General MR

Summary

The dashboards for istio were broken without the new "prometheus" vs "Prometheus" data source issue. This MR upgrades the built in charts to ensure that the datasource is correctly set for both normal prometheus and thanos.

Relevant logs/screenshots

N/A

Linked Issue

Relates #147 (closed)

Upgrade Notices

Grafana pods need to be manually deleted and restarted so that it pulls in the new configmap with the correct dashboard json changes.