bugfix: downgraded grafana version to 8.3.5

- 8.4.1 is not backwards compatible

roles/prometheus/defaults/main.yml

@@ -6,7 +6,7 @@ prometheus_image_version: "v2.33.4"
 
 # https://github.com/grafana/grafana
 grafana_image_name: "grafana/grafana"
-grafana_image_version: "8.4.1"
+grafana_image_version: "8.3.5"
 
 # https://github.com/prometheus/alertmanager
 alertmanager_image_name: "prom/alertmanager"