dashboards as cfg: disable loading dashboards from disk by default

conf/dashboards/dashboards.yaml

-- name: 'default'
-  org_id: 1
-  folder: ''
-  type: file
-  options:
-    folder: /var/lib/grafana/dashboards
+# - name: 'default'
+#   org_id: 1
+#   folder: ''
+#   type: file
+#   options:
+#     folder: /var/lib/grafana/dashboards
\ No newline at end of file