sink: Invert priorities to prefer external devices

sink: Invert priorities to prefer external devices

Currently internal > speaker > headphone and pci > usb > bluetooth.
Invert both of these sets, with the reasoning that a headphone and
speakers are something that a user has actively attached and should
therefore get a higher priority. The same reasoning is applied for
the bus type, i.e. bluetooth and usb should be higher than pci,
because they most likely have been actively attached be a user.

BugLink: https://bugs.freedesktop.org/show_bug.cgi?id=99222