PulseAudio crashes on startup and the fix [^1] has been sitting unmerged for
many weeks despite pings. PipeWire works fine, so this change forces it to
be used.
PW works fine for Phosh and SXMO at least (with one exception [^2]),
and long term we want to switch from PA to PW anyway, so this just
hastens that switch.
Fixes#2968
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[^1]: https://gitlab.alpinelinux.org/alpine/aports/-/merge_requests/68586
[^2]: On Phosh, using pw-pulse causes the volume slider in
the top pulldown panel to not work sometimes. This will likely be fixed in
the systemd branch once pw-pulse is started via socket activation,
since it is likely a race between phosh connecting to the pw-pulse socket
and pw-pulse binding it.