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>.
Restore help for --service-account-private-key-file flag, avoid incorrect deprecation notice
https://github.com/kubernetes/kubernetes/pull/60270/files#diff-fc9db90cc6b68d7c3ca838a8512447e9R61 incorrectly merged the ServiceAccountKeyFile flag used by the cloud controller manager (deprecated and scheduled to be removed in 1.10), and the one used by the kube-controller-manager (not deprecated, still supported)
This made the help for the supported flag disappear from 1.11 help output.
This PR:
* moves the option to the service account controller options
* removes the incorrect deprecation notice
* drops the option from the cloud-controller-manager
```release-note
The deprecated `--service-account-private-key-file` flag has been removed from the cloud-controller-manager. The flag is still present and supported in the kube-controller-manager.
```
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