(Photo: Eric Woolsey) For their 2024 mainstage summer festival season, Opera Theatre Saint Louis (OTSL) paired two fixtures in top-ten performance frequency, “The Barber of Seville” and “La Bohème,” with two exciting, less offered menu items. Philip Glass’s “Galileo Galilei” (2002) received just its fourth staging anywhere, while George Frideric Händel’s operatic capolavoro, “Julius Caesar” (“Giulio Cesare in Egitto,” 1724) {…}