The Metropolitan Opera’s production of Handel’s “Rodelinda,” created in 2004 as a showcase for the soprano Renée Fleming, went a long way toward establishing Baroque opera — and with it, elements of period performance practice — as something more than a novelty item at the house. So it is fitting that as the Met prepares a grand antiquarian experiment — “The Enchanted Island,” a Baroque-style pastiche with music by Handel, Vivaldi, Rameau and others, to open on New Year’s Eve — the signal “Rodelinda” production should usher it in, in a revival that opened on Monday evening.