2404 linux: install pulseaudio-utils

[aerickson]

pipewire has replaced pulseaudio on 2404, but we have tests that want to use pactl.
not sure if they'll work with pactl fronting pipewire, but give it a try.

Discovered via https://phabricator.services.mozilla.com/D289027.

[jcristau]

This matches what we're doing in-tree for the docker tests fwiw (https://searchfox.org/firefox-main/rev/26c440c6196eb0b428928d995395c97101d393f4/taskcluster/docker/recipes/ubuntu2404-test-system-setup-base.sh#73)

[jcristau]

For further reference, as of https://bugzilla.mozilla.org/show_bug.cgi?id=1924806 / mozilla-firefox/firefox@f575ec2, mochitest uses pactl info to figure out whether the system uses pulseaudio or pipewire. In the pipewire case it uses pw-cli and pw-dump to manage the dummy audio devices.