The Harry Potter movies are leaving HBO Max later this month and heading to NBCUniversal's new streaming service Peacock in October -- though they won't stay there long. Vulture reports that all eight films about the boy wizard will remain on Peacock for at least a month before returning to the service again next year as part of a six-month window in which Peacock will have subscription VOD rights to the series. Many believed that the Harry Potter movies would live forever on HBO Max since they are Warner Bros. titles. However, while HBO Max's parent company …