LONDON—After all those doubts about his future at Manchester United, Ole Gunnar Solskjær achieved what Pep Guardiola and Jürgen Klopp couldn’t do on Saturday: Win in the Premier League. It just needed United to face a Tottenham side devoid of any attacking ingenuity that allowed Cristiano Ronaldo and Edinson Cavani—with a combined age of 70—to…