Sheet Pan Chicken Meatballs with Tomatoes and Chickpeas

Name: Sheet Pan Chicken Meatballs with Tomatoes and Chickpeas
Ingredients: 6 tablespoons jarred harissa paste, such as Mina, divided; 1 large egg; ½ cup panko (Japanese breadcrumbs); 6 ounces feta in brine plus ¼ cup brine, cheese crumbled, divided; ⅔ cup chopped parsley, divided; 6 tablespoons olive oil, divided; 3 garlic cloves, divided; 1 teaspoon kosher salt, plus more; Freshly ground black pepper; 1 pound ground chicken; 1 pint mixed cherry tomatoes, halved if large; 1 15-ounce can chickpeas, rinsed, drained