Automatic merge from submit-queue (batch tested with PRs 47850, 47835, 46197, 47250, 48284)

Populate endpoints for headless service with no ports

**What this PR does / why we need it**:
- populate endpoints with headless service (thanks @fraenkel for the original PR!)
- allow ports with headless service
- nits

**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, fixes #<issue_number>, ...)` format, will close that issue when PR gets merged)*: fixes #32796 https://github.com/kubernetes/kubernetes/issues/32796#issuecomment-270462724

**Special notes for your reviewer**:
/cc @thockin @fraenkel 
**Release note**:

```release-note
NONE
```