Automatic merge from submit-queue. 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>.

core/v1 should be first in the discovery order

Currently, `core/v1` is at the end of the discovery order.

See https://github.com/kubernetes/kubernetes/issues/42521#issuecomment-360517775.

**Release note**:

```release-note
NONE
```

/assign sttts liggitt