Make phantoms not spawn by default, rather than the other way around.

Given the lack of interest in fixing the phantom's mechanics for years by now, and how hated it still is, a quick approach to stop annoying players who don't want to cheat is to make the 'don't spawn phantoms' toggle be enabled by default. This way, the majority of the playerbase would have a better Minecraft experience, while the minorities would still be able to enable their spawning if they really want too.