Fix Grafana dashboard/datasource label

roles/matrix-grafana/templates/dashboards.yaml.j2

@@ -1,7 +1,7 @@
 apiVersion: 1
 
 providers:
-  - name: {{ matrix_domain }} - Dashboards
+  - name: {{ matrix_server_fqn_matrix }} - Dashboards
     folder: '' # The folder where to place the dashboards
     type: file
     allowUiUpdates: true

roles/matrix-grafana/templates/datasources.yaml.j2

@@ -1,7 +1,7 @@
 apiVersion: 1
 
 datasources:
-  - name: {{ matrix_domain }} - Prometheus
+  - name: {{ matrix_server_fqn_matrix }} - Prometheus
     type: prometheus
     # Access mode - proxy (server in the UI) or direct (browser in the UI).
     access: proxy