[InterleaveAccess] Copy fast math flags when adjusting binary operators in interleave access pass

The Interleave Access pass will convert shuffle(binop(load, load)) to
binop(shuffle(load), shuffle(load)), in order to create more
interleaving load patterns (VLD2/3/4) that might have been messed up by
instcombine. As shown in D104247 we were missing copying IR flags to the
new instruction though, which should just be kept the same as the
original instruction.

Differential Revision: https://reviews.llvm.org/D104255