[GVN] Pre-commit test case showing miscompile in github issue #57025

This commit adds a reproducer for
  https://github.com/llvm/llvm-project/issues/57025
showing a miscompile in GVN.

Not sure how likely this kind of faults would be in a normal pipeline,
considering that the input IR has some dead code in it. On the other
hand, GVN itself sometimes creates dead basic blocks when splitting
critical edges. Anyway, the fault was found when doing fuzzy testing
using random pass pipelines.

Differential Revision: https://reviews.llvm.org/D131775