Rollup merge of #132210 - notriddle:notriddle/doctest-span-hack, r=GuillaumeGomez

rustdoc: make doctest span tweak a 2024 edition change

Fixes #132203

This is a compatibility hack, because I think the new behavior is better. When an A `include_str!` B, and B `include_str!` C, the path to C should be resolved relative to B, not A. That's how `include!` itself works, so that's how `include_str!` with should work.

Author: workingjubilee