[grafana] Update Grafana to 12.0.0 (#3700)

Co-authored-by: Jan-Otto Kröpke <[email protected]>

Author: terop

charts/grafana/Chart.yaml

@@ -1,7 +1,7 @@
 apiVersion: v2
 name: grafana
-version: 8.15.0
-appVersion: 11.6.1
+version: 9.0.0
+appVersion: 12.0.0
 kubeVersion: "^1.8.0-0"
 description: The leading tool for querying and visualizing time series and metrics.
 home: https://grafana.com