 WHERE THEY SING ALL DAY  AND GO TO THE OPERA AT NIGHT." What follows is a musical number  featuring bits and pieces from Leoncavallos "Pagliacci" performed  by "everyday" Italians. A street sweeper sings part of the prologue  ("Un nido di memorie...") as he greets a man who then hands out  opera tickets to a group of children emerging from a store; the kids  respond with "la