[SLP]Fix PR64519: Unexpected reordering of gathers.

The issue is actually related to ScatterVectorize nodes. If such node
gets reordered during bottom-to-top reordering, it may have associated
non-empty ReorderIndices. In this case, such nodes need to be handled
the same way as regular Vectorize nodes, not NeedToGather nodes. In this
case we need to reorder ReorderIndices array rather than scalars.