there seem to be a regression with Docker: the volume is not propagated anymore with
pre-existing files when a unix socket is inside.
This is the case in `backend-dev` with the D-Bus unix socket put in
`/home/libervia/.local/share/libervia/dbus_socket`, when the volume is mounted at
`/home/libervia/.local/share/libervia/`, resulting in hard to debug failures.
To work around that, the socket is not put in the volume mount point anymore, and has been
moved to `/home/libervia/.local/share/`
f0a0575f68