CoreDNS deployment label is incorrect

[idanlevin]

Is this a request for help?:
yes

Is this an ISSUE or FEATURE REQUEST? (choose one):
issue

What version of aks-engine?:
0.28.1

Kubernetes version:
1.12.1

What happened:
CoreDNS has replaced kube-dns, however, the deployment label is still k8s-app: kube-dns instead of k8s-app: coredns, which leads to mis-configuration in other products such as prometheus-operator

What you expected to happen:
The deployment label should be k8s-app: coredns

How to reproduce it (as minimally and precisely as possible):

1. Create a Kubernetes deployment using AKS-Engine
2. Execute the command: kubectl describe deploy -n kube-system coredns
3. Under the Labels category you will see:

Labels:             addonmanager.kubernetes.io/mode=Reconcile
                        k8s-app=kube-dns
                        kubernetes.io/cluster-service=true
                        kubernetes.io/name=CoreDNS

Anything else we need to know:

[idanlevin]

Seems to be by design -
coredns/deployment#116