A parent task uses `withTaskGroup` and adds three child tasks, but the body returns after awaiting only the first result via `group.next()`. Under structured concurrency rules, what happens to the two child tasks that were never awaited when the group scope exits?
await withTaskGroup(of: Int.self) { group in
group.addTask { await work(1) }
group.addTask { await work(2) }
group.addTask { await work(3) }
return await group.next()!
}