If there was a transfer that summed up the summer business from Celtic, then it’s Gustaf Lagerbielke. The 23-year-old was brought in to become a starter under Brendan Rodgers and compete alongside Cameron Carter-Vickers at the back for Celtic. But fast forward to the present and Gustaf Lagerbielke has seen one academy star in Stephen Welsh, as well as the previously unfancied Liam Scales, push ahead of him in the pecking order. The latter has outshone him and showcased how it should be done. Yes, he had that moment against Feyenoord and it’s a winning goal that helped end Celtic’s barren run i…