[llvm] [CodeGen] Port AtomicExpand to new Pass Manager (PR #71220)

[via llvm-commits]

paperchalice wrote:

> Should I revert the formatting changes in `llvm/include/llvm/CodeGen/Passes.h` ? most of the formatting changes done are not related to this PR but were still being detected by `check_code_formatter` so I had to comply.

Just use `git clang-format` to format the staged change.

https://github.com/llvm/llvm-project/pull/71220