SPOILER ALERT: The following piece contains plot details from the series finale of “ The Comeback ,” now streaming on HBO Max. Five minutes before the credits roll, “The Comeback” is set to end on a grim note. Valerie Cherish, the sitcom actor and pioneering reality star played with insistent cheer by comedic master Lisa Kudrow, is in a trap. She’s finally the face of a hit show, the classical multi-camera “How’s That?!” on the streaming service NuNet. But she’s also the face of television written by artificial intelligence, a fact over 70% of the audience seems to have no problem with.  In signing this Faustian bargain, Valerie has been hoisted by her own petard. Once she finally decides she can’t live with robot-written scripts — only after NuNet chief Brandon (Andrew Scott) insults her home turf of sitcoms as “easy-peasy” shows that “don’t need genius” — Valerie tries to walk away, only to learn that she, too, can be replaced by AI.…