Automatic merge from submit-queue.

Automated cherry pick of #63049: renable nodeipam in kube-controller-manager

**What this PR does / why we need it**:
Re-enables nodeipam controller for external clouds. Also does a small refactor so that we don't need to pass in `allocateNodeCidr` into the controller. 

Cherry pick of https://github.com/kubernetes/kubernetes/pull/63049 which fixes a critical bug in v1.10 that blocks external clouds from running nodeipam controller. 

**Release note**:
```release-note
Re-enable nodeipam controller for external clouds. 
```