Arsenal won’t be playing European football this season for the first time in quarter of a century. The Gunners went backwards under Mikel Arteta last season and the future of club captain Pierre-Emerick Aubameyang hangs in the balance. A weak defence and inconsistency have been a huge problem for the North London club. But with only a handful of players at Euro 2020 and the 2021 Copa America this summer and no trips abroad during the season, a well-rested squad…