Automatic merge from submit-queue (batch tested with PRs 66973, 67704, 67722, 67723, 63512). If you want to cherry-pick this change to another branch, please follow the instructions <a href="https://github.com/kubernetes/community/blob/master/contributors/devel/cherry-picks.md">here</a>.

Populate internal DNS names in GCE provider

Both VM name and hostname are internally routable.

**What this PR does / why we need it**: GCE cloud provider only populated IP addresses for instances. This PR adds internal DNS names. DNS names are used e.g. in kubelet server certificates (https://github.com/kubernetes/kubernetes/blob/5b77996433e8e8e07a7b0a9f7436fd44da2cad9c/pkg/kubelet/kubelet.go#L385)

**Release note**:
```release-note
NONE
```