Lane column can be removed from downstream processes after lanemerge

[jfy133]

@mashehu pointed out during release review of 2.2 (#573 (comment)) that we stop using the lane variable after lanemerge, so it's rather unncessary to keep.

To simplify downstream processes should remove this from each step where it is not required.

[jfy133]

Going to close this because this will likely be replaced via DSL2 anyway!