Add RPFilter to ISO kernel - required for modern Calico releases

[edge0701]

Fixes #6673.

[k8s-ci-robot]

Hi @edge0701. Thanks for your PR.

I'm waiting for a kubernetes member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

Once the patch is verified, the new status will be reflected by the ok-to-test label.

I understand the commands that are listed here.

Instructions for interacting with me using PR comments are available here. If you have questions or suggestions related to my behavior, please file an issue against the kubernetes/test-infra repository.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is NOT APPROVED

This pull-request has been approved by: edge0701
To complete the pull request process, please assign ra489
You can assign the PR to them by writing /assign @ra489 in a comment when ready.

The full list of commands accepted by this bot can be found here.

Needs approval from an approver in each of these files:

• OWNERS

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[minikube-bot]

Can one of the admins verify this patch?

[codecov-io]

Codecov Report

Merging #6690 into master will increase coverage by 0.09%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #6690      +/-   ##
==========================================
+ Coverage   38.56%   38.66%   +0.09%     
==========================================
  Files         142      142              
  Lines        8642     8659      +17     
==========================================
+ Hits         3333     3348      +15     
- Misses       4893     4895       +2     
  Partials      416      416

Impacted Files	Coverage Δ
cmd/minikube/cmd/delete.go	26.19% <0%> (+0.82%)	⬆️
pkg/minikube/machine/cache_binaries.go	87.5% <0%> (+3.4%)	⬆️