Fix main dashboard

The double-quotes in the main_prometheus dashboard do not need to be
escaped.  It just results in double-escaping in the actual Grafana
dashboard which breaks things:
  expr: avg(openstack_api_check_status{service=~\\"keystone.*public.*\\"})

Change-Id: Ia8ba02c081bf51b785dcd22a75040d540f00e4c3
diff --git a/keystone/meta/grafana.yml b/keystone/meta/grafana.yml
index cf147a0..88bc7c1 100644
--- a/keystone/meta/grafana.yml
+++ b/keystone/meta/grafana.yml
@@ -37,7 +37,7 @@
               type: dashboard
             target:
               cluster_status:
-                expr: avg(openstack_api_check_status{service=~\"keystone.*public.*\"})
+                expr: avg(openstack_api_check_status{service=~"keystone.*public.*"})
   service_level:
     datasource: influxdb
     row: