Automatic merge from submit-queue (batch tested with PRs 63920, 63716, 63928, 60553, 63946). 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>.

Update kubeadm's minimum supported Kubernetes in v1.11.x to 1.10

**What this PR does / why we need it**:
This PR does,

* Restricts supported Kubernetes version in 1.11 cycle;
* Removes useless v190-specific variables, since the minimum version is v1.10;
* Bumps etcd version based on k8s version to 1.10.X => 3.1.12, 1.11.X => 3.2.18, 1.12.X => 3.2.18;

**Which issue(s) this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close the issue(s) when PR gets merged)*:
Fixes kubernetes/kubeadm#815

**Special notes for your reviewer**:
/cc kubernetes/sig-cluster-lifecycle-pr-reviews
/cc luxas 
**Release note**:

```release-note
Update kubeadm's minimum supported kubernetes in v1.11.x to 1.10
```