Add ability to configure notification workers

Change-Id: I38e9c8a337f963dd3519fe2fc1c8e882405c8bb1
Related-Prod: https://mirantis.jira.com/browse/PROD-23449
diff --git a/tests/pillar/server_cluster.sls b/tests/pillar/server_cluster.sls
index 6aec6f1..be5f1bb 100644
--- a/tests/pillar/server_cluster.sls
+++ b/tests/pillar/server_cluster.sls
@@ -60,6 +60,7 @@
         host: 127.0.0.4
         port: 8086
     notification:
+      workers: 8
       batch_timeout: 10
       batch_size: 100
       policy: