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