fix grafana var in group vars

Author: aine-etke

group_vars/matrix_servers

@@ -5599,7 +5599,7 @@ grafana_container_labels_traefik_tls_certResolver: "{{ traefik_certResolver_prim
 
 grafana_container_http_host_bind_port: "{{ (matrix_playbook_service_host_bind_interface_prefix ~ '3000') if matrix_playbook_service_host_bind_interface_prefix else '' }}"
 
-grafana_provisioning_datasources: |
+grafana_provisioning_datasources_datasources: |
   {{
     ([{
       'name': (matrix_server_fqn_matrix + ' - Prometheus'),