[InstCombine] Do not perform binop-of-shuffle when mask is poison

A miscompilation issue has been addressed with refined checking.
Shuffle masks operand may be turned into `poison` if this does
not lead to observable changes. This however may not guarantee
binop to binop-of-shuffle replacement to be sound anymore.

Fixes: https://github.com/llvm/llvm-project/issues/82052.