Walt Disney Co.’s underwhelming theme-park attendance last quarter was the latest sign that the intergalactic saga isn’t resonating for younger generations raised on Iron Man and Fortnite. Chief Executive Officer Bob Iger was so sure fans would be blasting through the door that he had instituted a reservation system for visitors to enter Star Wars: Galaxy’s Edge, the new attraction at Disneyland. It turned out not to be necessary.Star Wars toy sales popped with 2015’s “The Force Awakens,” the start of a trilogy that united Han, Luke and Leia with a new band of heroes, but have slumped since. “Solo: A Star Wars Story,” last year’s spinoff featuring the backstory of beloved characters, utterly bombed. “The Last Jedi,” the second in the new trilogy, was profitable but fell shy of its predecessor’s performance. The next installment, “The Rise of Skywalker,” will have the very future of the franchise riding on it when it debuts in December.