Improve k8s master deployment workflow

[qiluo-msft]

          I see the point of `first_boot_flag`, `kubernetes_master_entrance.sh` and `sed -i '/^exit 0/i\bash /usr/sbin/kubernetes_master_entrance.sh' $FILESYSTEM_ROOT/etc/rc.local`.

They are introduced for a deployment workflow, but this workflow is fragile. Suggest:

1. Create and start the Kubernetes master VM
2. Configure the VM IP by hyperv-daemons, or by console access
3. SSH into the VM, so you have full control
4. Copy some scripts into the VM
5. Enable/start some services.

Originally posted by @qiluo-msft in #15716 (comment)