Suggest creating a copy of the branch before starting rebase to remove secrets

What does this MR do and why?

Suggest creating a copy of the branch before starting the rebase process. Also suggest watching a short demo.

This work is being done in support of the https://gitlab.com/gitlab-com/gitlab-OKRs/-/work_items/7095+s OKR and specifically this comment thread: https://gitlab.com/gitlab-com/gitlab-OKRs/-/work_items/7095#note_1988903714

MR acceptance checklist

Please evaluate this MR against the MR acceptance checklist. It helps you analyze changes to reduce risks in quality, performance, reliability, security, and maintainability.