An exterminator found a rotting corpse wedged in the chimney of a Queens public school Tuesday morning after he was called to investigate a putrid odor, cops and sources said. The pest control worker made the grisly discovery just before 9 a.m. when a janitor dispatched him to P.S./I.S. 113 Anthony J. Pranzo at 87 Street and 78 Avenue in Glendale to investigate the stench, according to authorities and law enforcement sources. The exterminator opened the ash dump and found a shoe, then felt a