Scrub k3s-config.yaml from repo

[JacksonWrath]

Since the server token of a k3s cluster cannot be changed, it needs to be scrubbed from the repo.

Based on some research, I believe this is what I'll have to do:

• https://github.com/newren/git-filter-repo/blob/main/Documentation/converting-from-filter-branch.md#removing-a-file

  git filter-repo --invert-paths --path k3s-config.yaml

• Re-sign them all

  git filter-branch -f --commit-filter 'git commit-tree -S "$@";' 

• Remove replace refs

  git filter-repo --replace-refs delete-no-add

• Expire unreachable refs, and garbage collect:

  git reflog expire --expire-unreachable=now --all
  git gc --prune=now

• Add origin back and force push
• Garbage collect on the server

[JacksonWrath]

Done.

[JacksonWrath]

Post closure update: had to rebuild the cluster anyway, so even if I missed something in this procedure, the token is no longer valid.