CI: enable virtual audio sink for soundd (#31120)

* enable virtual sound

* mv install to dockerfile

* cleaner

---------

Co-authored-by: Justin Newberry <justin@comma.ai>
old-commit-hash: 403610eed968823aff507d44e4945be774c6fb37

selfdrive/test/setup_vsound.sh

@@ -0,0 +1,10 @@
+#!/bin/bash
+
+{
+  #start pulseaudio daemon
+  sudo pulseaudio -D
+
+  # create a virtual null audio and set it to default device
+  sudo pactl load-module module-null-sink sink_name=virtual_audio
+  sudo pactl set-default-sink virtual_audio
+} > /dev/null 2>&1