set pool ops alerts optional and disable as default

Change-Id: Ib9ba4b2142bd6cba278e3674619cd5c2ac4b6121
Related-PROD: PROD-23935
diff --git a/metadata/service/monitoring/cluster_stats.yml b/metadata/service/monitoring/cluster_stats.yml
index 85ae108..fdca597 100644
--- a/metadata/service/monitoring/cluster_stats.yml
+++ b/metadata/service/monitoring/cluster_stats.yml
@@ -8,5 +8,7 @@
   ceph:
     monitoring:
       cluster_stats:
+        extra_alerts:
+          enabled: false
         enabled: true
         ceph_user: ${_param:ceph_monitoring_user}