Group alerts in Alertmanager by alertname and instance

Change-Id: Id2f062bccbe9c3bdb246784631746cd3b6992a63
diff --git a/metadata/service/alertmanager/container.yml b/metadata/service/alertmanager/container.yml
index f5a0bff..6bc18aa 100644
--- a/metadata/service/alertmanager/container.yml
+++ b/metadata/service/alertmanager/container.yml
@@ -14,7 +14,7 @@
         global:
           resolve_timeout: 5m
         route:
-          group_by: ['region', 'service']
+          group_by: ['alertname', 'instance']
           group_wait: 60s
           group_interval: 5m
           repeat_interval: 3h