Rename "master" branch to "main"

[dims]

Steps and check list are here:
https://www.kubernetes.dev/resources/rename/

[dims]

/assign @kubernetes/owners

[spiffxp]

/wg naming
umbrella issue ref: kubernetes/org#2222

For future reference it would be helpful if you can confirm you've walked through the checklist. Noting for @kubernetes/owners that the instructions as posted at kubernetes.dev are not easily copy-pasteable into an issue body as a checklist.

That said, I took a quick grep through kubernetes/klog and kubernetes/test-infra, and can't see that you'll have any pre/post migration changes to make. So +1 as a member of @kubernetes/owners

Things I would suggest adding to the body:

- [x]  Once all non-disruptive tasks have been completed and disruptive tasks have been identified, assign the GitHub Management team (@kubernetes/owners) for approval.
- [x] Once the issue has been approved, send a notice to your SIG’s mailing list about the potential branch rename.
- [x] Rename the default branch from master to main using the GitHub UI by following the official instructions.
- [x] Trial the local development experience with a pre-rename clone.
- [x] Send a notice about the branch rename to your SIG’s mailing list. Include the link to the GitHub instructions to rename your local branch.

[dims]

Note to sig-instrumentation mailing list - https://groups.google.com/g/kubernetes-sig-instrumentation/c/GmdVotAvZTw/m/wgpOM35mAgAJ

[spiffxp]

/sig instrumentation
/priority important-soon
/kind cleanup

[dims]

Done!