Automatic merge from submit-queue
etcd3: use PrevKV to remove additional get
ref: #https://github.com/kubernetes/kubernetes/issues/33653
We are trying to test using PrevKV feature and see if it improves performance.
In order to test this, we will need etcd v3.1 (alpha) image.
Blockers:
- update gcr.io image (version v3.0.12)