[Analysis] remove bogus smin/smax pattern detection

This is a revert of cfcc42bd. The analysis is wrong as shown by
the minimal tests for instcombine:
https://alive2.llvm.org/ce/z/y9Dp8A

There may be a way to salvage some of the other tests,
but that can be done as follow-ups. This avoids a miscompile
and fixes #54311.