It's handled the other way around than old aout modules.

By default, "volume-save" is true and we keep the current behavior (the volume
is saved by Windows for this session). If "volume-save" is false, then we use
the prefered volume set by the user "mmdevice-volume" and don't use the VLC
audio session.

Fixes #19664

(cherry picked from commit aba1b014

)
Signed-off-by: Thomas Guillem <thomas@gllm.fr>