Automatic merge from submit-queue (batch tested with PRs 61725, 63261). 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>.
Use cloudprovider.NotImplemented in AddSSHKeyToAllInstances
**What this PR does / why we need it**:
Minor cleanup: In looking at implementations of this method,
noticed a few providers created their own errors instead of using cloudprovider.NotImplemented
**Release note**:
```release-note
NONE
```