Update foldFMulReassoc to respect absent fast-math flags (#88589)

This change updates a few of the transformations in foldFMulReassoc to
respect absent fast-math flags in cases where fmul and fdiv, fadd, or fsub
instructions were being folded but the code was only checking for
fast-math flags on the fmul instruction and was transferring flags to
the folded instruction that were not present on the other original 
instructions.

This fixes https://github.com/llvm/llvm-project/issues/82857