NEW YORK (Reuters) – Actresses Valerie Harper, who is suffering from cancer, and Leah Remini will join reality TV star Nicole “Snooki” Polizzi and former NFL player Keyshawn Johnson for the 17th season of the hit TV competition “Dancing With the Stars.” The celebrities, whose names were announced Wednesday on ABC’s “Good Morning America,” are among 12 celebrities who will be paired with professional dancers on the show that will premiere on the ABC network on September 16. …