Automatic merge from submit-queue
WIP: Remove the legacy networking mode
<!-- Thanks for sending a pull request! Here are some tips for you:
1. If this is your first time, read our contributor guidelines https://github.com/kubernetes/kubernetes/blob/master/CONTRIBUTING.md and developer guide https://github.com/kubernetes/kubernetes/blob/master/docs/devel/development.md
2. If you want *faster* PR reviews, read how: https://github.com/kubernetes/kubernetes/blob/master/docs/devel/faster_reviews.md
3. Follow the instructions for writing a release note: https://github.com/kubernetes/kubernetes/blob/master/docs/devel/pull-requests.md#release-notes
-->
**What this PR does / why we need it**:
Removes the deprecated configure-cbr0 flag and networking mode to avoid having untested and maybe unstable code in kubelet, see: #33789
**Which issue this PR fixes** *(optional, in `fixes #<issue number>(, #<issue_number>, ...)` format, will close that issue when PR gets merged)*:
fixes#30589fixes#31937
**Special notes for your reviewer**: There are a lot of deployments who rely on this networking mode. Not sure how we deal with that: force switch to kubenet or just delete the old deployment?
But please review the code changes first (the first commit)
**Release note**:
<!-- Steps to write your release note:
1. Use the release-note-* labels to set the release note state (if you have access)
2. Enter your extended release note in the below block; leaving it blank means using the PR title as the release note. If no release note is required, just write `NONE`.
-->
```release-note
Removed the deprecated kubelet --configure-cbr0 flag, and with that the "classic" networking mode as well
```
PTAL @kubernetes/sig-network @kubernetes/sig-node @mikedanese
61e0113019