[llvm] Fix crash in install_bad_alloc_error_handler (PR #83160)

[Alexandre Ganea via llvm-commits]

https://github.com/aganea commented:

> Sure! Do you have any recommendations on how to best "assert" no crash? It seems weird adding unittests without any assertions inside.

If you revert locally your fix in `ErrorHandling.cpp` a crash should fail the test. That is enough I think to cover the issue (along with an explanation like suggested below).

https://github.com/llvm/llvm-project/pull/83160