[llvm] Remove `br i1 undef` from regression tests (PR #115130)

[Nuno Lopes via llvm-commits]

https://github.com/nunoplopes requested changes to this pull request.

Great work, thanks!

The MemorySSA tests you changed to use the automatic output checking must be reverted. You must keep the old checks. The auto-generated ones aren't checking the same thing. The old ones were checking that the memory phis were in the right place.

https://github.com/llvm/llvm-project/pull/115130