Fix pulse tunnel unload segfaulting pipewire-pulse

This happens when a zeroconf service advertises a pulseaudio protocol tunnel when it does not serve it. That is nothing is listening on the advertised port. Then the tunnel module is unloaded but since commit f6e25c23 module-pulse-tunnel: don't unload module from pulse thread this makes pipewire-pulse segfault. See https://gitlab.freedesktop.org/pipewire/pipewire/-/issues/3199 This is triggered by a LibreElec 11.0.1 box that advertises a PulseAudio protocol tcp service on port 4713 but does not listen there.

This patch is already included in the upstream git repository in master.

This closes https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1035280