Cliff Lipson/CBS After 15 successful seasons, it’s time to talk about the end of The Talk. Akbar Gbajabiamila, Amanda Kloots, Natalie Morales, Jerry O’Connell and Sheryl Underwood are preparing to say goodbye to the long-running CBS series on Friday, December 20. Before that final episode tapes, however, the cohosts are looking back on their unforgettable…