Rolling ugprade is an important feature for a managed k8s service,
at this stage, two user cases will be covered:
1. Upgrade base operating system
2. Upgrade k8s version
Known limitation: When doing operating system upgrade, there is no
chance to call kubectl drain to evict pods on that node.
Task: 30185
Story: 2002210
Change-Id: Ibbed59bc135969174a20e5243ff8464908801a23
05c27f2d73