conf: Use .nofail when loading module-jackdbus-detect

conf: Use .nofail when loading module-jackdbus-detect

When starting via a console login, PA will likely not have a session DBus
to play with. As there is no X11 environment, libdbus will be unable
to launch a session DBus for us and thus the module will fail to load
which in turn prevents PA from loading.

If the user subsequently logs into X11 this it will still not be possible
to load the module as the server will be ignorant of the X11 and DBus
environment variables so a longer term solution for handling this should
be found.