By Veronika Bondarenko Popeyes is bringing back a heat-heavy item from its past. When it comes to spice, fast-food chains have to navigate marketing power with a menu that needs to be palatable to the a wide American audience. The truly, burn-your-mouth spice is rarely found at mainstream chains while something that inches closer to the top of the Scoville scale are usually reserved for limited-time only items and other brief promotions. A year ago, Arby’s of Inspire Brands briefly had a Diablo Dare sandwich so spicy as to need something to “cool your mouth down between bites.” (A small vanill…