Automatic merge from submit-queue (batch tested with PRs 42200, 39535, 41708, 41487, 41335)
[Federation][Kubefed] Flag cleanup
This PR is for the issue https://github.com/kubernetes/kubernetes/issues/41333
**Special notes for your reviewer**:
@marun @madhusudancs
**Release note**:
```
Kubefed init unlearned the following flags:
--storage-backend
Users should instead use the following flag to pass additional arguments:
--apiserver-arg-overrides to api server
```
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