Prometheus reader

in continuing to #7064
using the right prometheus sa, with view privileges.

roles/openshift_grafana/defaults/main.yaml

@@ -4,7 +4,7 @@ openshift_grafana_state: present
 openshift_grafana_namespace: grafana
 openshift_grafana_pod_timeout: 300
 openshift_grafana_prometheus_namespace: "{{ openshift_prometheus_namespace | default('openshift-metrics') }}"
-openshift_grafana_prometheus_serviceaccount: prometheus
+openshift_grafana_prometheus_serviceaccount: prometheus-reader
 openshift_grafana_serviceaccount_name: grafana
 openshift_grafana_serviceaccount_annotations: []
 l_openshift_grafana_serviceaccount_annotations: