For most football teams, preseason action consists of honing in on cadences, getting reps at game speed, and determining spots on the depth chart.This year, the final regular season tune up will be the most important game on the Windham, N.H., high school football team’s schedule.The Jaguars will be the first football team from New England to play internationally when they compete in the Global Ireland Football Tournament in Dublin on Friday.“Usually the first game is a 10-on-10 scrimmage,” said sixth-year Windham coach Jack Byrne, a Tewksbury native. “Now all of a sudden, it’s the biggest game that we’ve ever…