So that all nodes attach to some driver to be scheduled.
For the virtual sink/sources this is a normal thing and we can remove
the custom settings.
For normal stream, this now makes it possible to link pw-play directly
to pw-record and have it transport data.
Fixes#1761
For the modules that require a driver, don't add ourselves to
the pipewire.dummy group but instead just use the NODE_WANT_DRIVER
property to be assigned to a driver.
This makes it possible for the nodes to move to another driver than the
dummy driver (which has very high priority) and it avoids resampling in
cases where the nodes are linked to an audio source or sink.
