©Dominic McLaughlin as Harry Potter. Aidan Monaghan/HBO Warner Bros. has begun production on HBO’s ‘Harry Potter’ TV show, which marks the long-awaited return of J.K. Rowling’s wizarding world. Harry Potter and the Deathly Hallows: Part 2 concluded its journey on the big screen nearly 14 years ago when Harry Potter and the Deathly Hallows: Part…