Rollup merge of #121959 - sundeep-kokkonda:patch-2, r=davidtwco

Removing absolute path in proc-macro

With rust 1.75 the absolute build path name is embedding into proc-macro (.rustc section) and which causes reproducibility issues.
Detailed issue description is here - rust-lang/rust#120825 (comment)

With this change the 'absolute path' changed back to '/rust/$hash' format as in earlier revisions.