By Brian Straus The U.S. has learned its schedule for the Concacaf Nations League group stage, which doubles as part of the team’s preparations for the 2022 World Cup. The two-week June window that will comprise a significant part of the U.S. national team’s preparation for the Qatar World Cup will include a return trip to to El Salvador’s Estadio Cuscatlán, the site of the Americans’ raucous qualifying opener last year. Concacaf on Wednesday afternoon unveiled the schedule for the second edition of its Nations League, a three-tiered tournament designed to provide additional competitive opport…