[DAG] visitVECTOR_SHUFFLE - MergeInnerShuffle - reset shuffle ops and reorder...

[DAG] visitVECTOR_SHUFFLE - MergeInnerShuffle - reset shuffle ops and reorder early-out and second op matching. NFCI.

I'm hoping to reuse MergeInnerShuffle in some other folds - so ensure the candidate ops/mask are reset at the start of each run.

Also, move the second op matching before bailing to make it simpler to try to match other things afterward.