docs: remove local miden-bank files (now ingested from miden-tutorials)

[Keinberger]

With #168 merged in miden-tutorials, the miden-bank tutorial files now get ingested via CI into docs/builder/tutorials/miden-bank/. The old local copy at docs/builder/tutorials/rust-compiler/miden-bank/ is still around, which means the next deploy would produce duplicate pages in the sidebar.

This needs to be cleaned up:

• Delete the local tutorials/rust-compiler/miden-bank/ directory
• Update the CI clean steps in deploy-docs.yml and cut-versions.yml to handle the new ingested path
• Add redirects for the old rust-compiler/miden-bank URLs
• Update internal links that still point to rust-compiler/miden-bank