lang/rust: Update to 1.86.0

Announce: https://blog.rust-lang.org/2025/04/03/Rust-1.86.0.html
ChangeLog: https://github.com/rust-lang/rust/releases/tag/1.86.0

Put back rustdoc in _RUST_TOOLS, rustdoc is an integral part of cargo
and has no connection with DOCS.

PR: 285381,285840
Tested by: mikael,pkubaj