kube-up.sh start scale-out cluster minion VM has external IP address

[sonyafenge]

What happened:
kube-up.sh start scale-out cluster minion VM has external IP address, this has security risk.

What you expected to happen:
kube-up.sh start scale-out cluster minion VM has no external IP address. kube-up.sh start scale-up cluster don't have external IP for minion VM.
How to reproduce it (as minimally and precisely as possible):

Anything else we need to know?:
this is caused by PR: #969

Environment:

• Arktos version (use kubectl version):
• Cloud provider or hardware configuration:
• OS (e.g: cat /etc/os-release):
• Kernel (e.g. uname -a):
• Install tools:
• Network plugin and version (if this is a network-related bug):
• Others: