/kind bug

What happened:
Given a kubelet configured with --cloud-provider=aws, --hostname-override=ldm-0110069 and --register-node=true, the kubelet still tries to register with the api server as the "aws-specified" hostname (for example ip-something.eu-west-1.compute.internal). This is problematic for custom provisioners if the configured node cert doesn't include the "aws-format" node name, as kube-apiserver won't allow the node to register. In general there's very little information in the docs about what the "cloud-provider" flag actually does, but IMHO it's pretty clear that the "hostname-override" flag should "win" (especially since that flag is explicitly documented while the cloud-provider flag isnt).

What you expected to happen:
Kubelet should register with the configured value of --hostname-override.

How to reproduce it (as minimally and precisely as possible):
Configure a kubelet on an aws instance with the flags listed above. In order to verify that this indeed caused by the cloud-provider flag, remove that flag from the kublet parameter and restart the kubelet service/pod. The kubelet is now able to register to the api with the name specified in hostname-override

Anything else we need to know?:

Environment:

• Kubernetes version (use kubectl version): 1.10.2
• Cloud provider or hardware configuration: aws
• OS (e.g. from /etc/os-release): ubuntu 16.04
• Kernel (e.g. uname -a):
• Install tools: custom
• Others: