Add restart of the td-agent to upgrade pipeline

In this change we are simply restartng td-agent process
on msg nodes to refresh td-agent session.

Change-Id: I478a6f0d3bb99a9ff4736d354558741e2666870c
PROD-related: PROD-33878
diff --git a/stacklight-upgrade.groovy b/stacklight-upgrade.groovy
index 7554530..9b2d760 100644
--- a/stacklight-upgrade.groovy
+++ b/stacklight-upgrade.groovy
@@ -229,5 +229,9 @@
                 }
             }
         }
+        stage('Post upgrade steps') {
+            common.infoMsg('Apply workaround for PROD-33878')
+            salt.runSaltProcessStep(pepperEnv, "I@fluentd:agent and I@rabbitmq:server", "service.restart", "td-agent", null, true)
+        }
     }
 }