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 (5b77996433/pkg/kubelet/kubelet.go (L385))
**Release note**:
```release-note
NONE
```
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