k8sdemo: Rerunning prepare.sh/setup_k8s_cluster.sh causes issues

[pkeerthana]

Rerunning prepare.sh and setup_k8s_cluster.sh on a k8s setup that is already up, causes cluster communication failure since netmaster dns entry is not present in /etc/hosts.

[reshmagiliyal]

I have run Prepare.sh and ./setup_k8s_cluster.sh 3 times in 8 k8s setups, but i did not face any issue.