more calming fireflies

I find the sound of fireflies really grating so I replaced it with a different Night Ambience sound. Initially made for Java snapshot 25w32a, should support every snapshot/version for a long time. Currently supports [pack_format](https://minecraft.fandom.com/wiki/Pack_format) values 65.1 to 900 (900 is an arbitrary number, but it should keep this pack from breaking for a long time).