[SLP]Fix PR61018: Assertion `Mask[I] == UndefMaskElem && "Multiple uses

of scalars."' failed.

Need to check for the reused indices when checking if 2 insertelement
instruction are from the same buildvector. If the inidices are reused,
better not to match buildvectors and consider them as differenet,
otherwise need to track the order of insertelement operations.