[EKS] [request]: Add Prometheus annotations to default coredns podspec

One issue I found with the default configuration of coredns in EKS is that the relevant Prometheus annotations are missing from the podspec. This is a relatively easy fix that will make it much easier for our users to see the metrics upon installing Prometheus into their clusters.

The patch follows:

```
apiVersion: extensions/v1beta1
kind: Deployment
spec:
template:
metadata:
annotations:
prometheus.io/port: "9153"
prometheus.io/scrape: "true"
```

Start by locating the default EKS CoreDNS Deployment podspec and compare it with the annotations shown in the issue. Done means the pod template includes the Prometheus port 9153 and scrape annotations, with the change verified in the relevant configuration.

Written by the indexing model from the issue text.