LAS VEGAS—Bradie Tennell is back on top of American figure skating. The 22-year-old Olympian, who had finished second and third at the past two national championships, followed her rollicking short program with a rock-solid free skate Friday night at the U.S. Figure Skating Championships. Tennell hit all seven of her triple jumps to finish with 232.61 points, well clear of her closest rivals Amber Glenn and Karen Chen. “I don’t even know where to start. I’m just so happy,” said Tennell, who has dealt with injuries and inconsistency since helping the U.S. win team bronze at the 2018 Winter Olympics. “That skate was everything I wanted to put out there. I was so happy and so grateful for everybody that helped me get here.” Glenn finished with 215.33 points to edge 2017 champion Karen Chen by 0.35 points for the silver medal, while two-time and defending champion Alysa Liu struggled …