Most baby mobs do not have unique sound events

Baby mobs use the same sounds as adult mobs, but pitch shifted to be higher. This is hardcoded, and cannot be modified by a resource pack to for example have different subtitles or even different sounds. The only exceptions to this are the baby turtle, which does have a unique sound event and subtitle, and the polar bear, which only partially qualifies due to having a unique baby idle sound. All baby mobs should follow the turtle's example.