To prepare the chicken, place the chicken breasts, garlic, ginger, scallions, and pineapple into a slow cooker. In a separate bowl, combine the chicken stock, soy sauce, sesame oil, and brown sugar. Whisk together to combine well. Pour this over the chicken, make sure everything is submerged, then cook on low for 6-8 hours.
To prepare the macaroni salad, bring a small pot of salted water to a boil, then add the macaroni. Cook for 10-12 minutes, until the pasta is fully cooked and soft. Drain the pasta, and allow to cool slightly. In a small bowl, combine the mayonnaise, sour cream, and celery salt. Whisk to blend well. Then, combine the cooked macaroni, grated carrot, and chopped green onion in a mixing bowl. Add the dressing, and toss everything together until well-combined and the pasta is completely coated. Cover and refrigerate until ready to serve.
When the chicken is done cooking, separate the cooking liquid and the chicken. Shred the chicken, and combine with as much of the cooking liquid as needed to keep the chicken moist.
To make the teriyaki glaze, heat the sesame oil in a small saucepan over medium-high, then add the chopped garlic, ginger, and pineapple. Saute until aromatic, about 1 minute. Next, add the brown sugar, soy sauce, mirin, and 2/3 of a cup of water. Stir to combine well, then bring the mixture to a simmer. In a small bowl or measuring cup, combine the remaining 1/4 cup of water and 1 1/2 tbsps of cornstarch. Whisk together to make a slurry. Once the teriyaki sauce has come to a simmer, pour the cornstarch mixture into the saucepan, stir, and cook for 2-3 minutes until the sauce thickens into a glaze-like texture. Strain into a bowl, and set aside until ready to serve.
To assemble the sliders, cut Hawaiian rolls in half and lightly toast. Transfer to a serving platter. Place shredded chicken on the bottom halves, then top with teriyaki glaze, macaroni salad, and top halves of the rolls.