Wait for kubernetes node will reach correct status during reboot

Change-Id: I7ce955acc3a2dfa00d8ea0c42f30b4a006dba3da
Related-PROD: PROD-28976 (PROD:28976)
(cherry picked from commit 1da4dd91c475b074323b42aac082d8558b39b1e9)
diff --git a/k8s-upgrade-pipeline.groovy b/k8s-upgrade-pipeline.groovy
index fe7d189..64a7d99 100644
--- a/k8s-upgrade-pipeline.groovy
+++ b/k8s-upgrade-pipeline.groovy
@@ -285,6 +285,13 @@
 
     stage("Rebooting ${target}") {
         debian.osReboot(pepperEnv, target)
+        /*
+            * Kubernetes controller manager will mark kubernetes node as NotReady
+            * only after 40 seconds of it's downtime.
+            * Let's wait for 60 sec to be sure that node will reach it's
+            * correct status.
+        */
+        sleep(60)
         common.retry(times, delay) {
             if(!isNodeReady(pepperEnv, target)) {
                 error("Node still not in Ready state...")