pulseaudio: don't enable network audio support for everyone by default

[MilhouseVH]

From @fritsch:

Are you guys sure you want this: https://github.com/LibreELEC/LibreELEC.tv/blame/85150686feda583445ee7ad35e687eb935865cda/packages/audio/pulseaudio/config/system.pa#L68
having PA open via tcp to everyone
so that every network sink can output via pulse's default device, e.g. BT headset?
...
If it's not a use-case that LE should provide
remove it
makes no sense to announce LE as tcp streaming target
without authentication

This module is needed for network audio, but probably shouldn't be enabled by default - anyone that needs network audio support can load this module themselves in autostart.sh, or via a systemd service.

I'll include this PR in nightly builds - let's see what (if anything) breaks.