Add alerting for RadosGW Usage Exporter metrics

Author: MoteHue

etc/kayobe/kolla/config/prometheus/ceph.rules

@@ -205,7 +205,6 @@ groups:
       description: "{{ $value }} OSD requests are taking too long to process (osd_op_complaint_time exceeded)"
 
 {% endraw %}
-
 {% if stackhpc_enable_radosgw_usage_exporter | bool %}
 - name: rgws
   rules: