Revert "[InstCombine] propagate 'nsw' on pointer difference of 'inbounds' geps (PR47430)"

This reverts commit 324a5320.

On closer examination of at least one of the test diffs,
this does not appear to be correct in all cases. Even the
existing 'nsw' creation may be wrong based on this example:
https://alive2.llvm.org/ce/z/uL4Hw9
https://alive2.llvm.org/ce/z/fJMKQS