Automatic merge from submit-queue (batch tested with PRs 43355, 42827)
kubeadm: In-cluster DNS should be used when self-hosting
**What this PR does / why we need it**:
I noticed that the master components doesn't use the built-in cluster DNS which they really should do in order to be able to discover other services inside the cluster (like extension API Servers like service catalog).
This is a really small change that fixes a misconfiguration that had slipped though earlier.
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #
**Special notes for your reviewer**:
**Release note**:
```release-note
NONE
```
@jbeda @bowei @MrHohn
049b35c92a