Backport v2024 <- v2025dev2: dh_setup_copyright: Strip trailing '/@/...' from Rust CUs

https://github.com/rust-lang/rust/pull/92024 appends a build-specific suffix to each compilation unit name in order to ensure they're all unique. Thus, in order to get the original filenames, we need to strip that suffix off.

In order to ensure the SBOM contains the right paths, we also write the modified sources back to the bin2sources file.

infrastructure/apertis-issues#456 (closed)

Signed-off-by: Ryan Gonzalez ryan.gonzalez@collabora.com