Auto merge of #125032 - compiler-errors:crash-dump-dir, r=onur-ozkan

Make crashes dump mir to build dir

Set `-Zdump-mir-dir` for `crashes`-style tests.

Alternatively, we just remove `tests/crashes/124436.rs`, since if the only way to get it to repro is via `-Zdump-mir`, then maybe it's not worth it to fix.

Fixes #125029

Author: bors