This teaches the interleaved access pass to the lower the intrinsics for
factors 4,6 and 8 added in #139893 to target intrinsics.
Because factors 4 and 8 could either have been recursively
[de]interleaved or have just been a single intrinsic, we need to check
that it's the former it before reshuffling around the values via
interleaveLeafValues.
After this patch, we can teach the loop vectorizer to emit a single
interleave intrinsic for factors 2 through to 8, and then we can remove
the recursive interleaving matching in interleaved access pass.
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