[main] rancher-backup start using rancher/kuberlr-kubectl

[mallardduck]

PR to implement here: #653

Note even after that is merged we need to:

1. Create a new RC tag on BRO for main,
2. Go make a PR to rancher/charts for dev-v2.11 to add new BRO rc,
3. Have QA test that after merging in charts repo,
4. Once validated they will close this issue.
   • If near release we can un-RC tag on BRO repo then do charts PRs; Otherwise,
   • Leave the RC for a likely follow up RC to BRO if we have more work landing