[LV] Strip wrap flags from vectorized reductions

[LV] Strip wrap flags from vectorized reductions

A sequence of additions or multiplications that is known not to wrap, may wrap
if it's order is changed (i.e., reassociated). Therefore when vectorizing
integer sum or product reductions, their no-wrap flags need to be removed.

Fixes PR43828

Patch by Denis Antrushin

Differential Revision: https://reviews.llvm.org/D69563