Not all binding implementations follow the requirements of fdb_stop_network

In the current C API, it is required that `fdb_stop_network` be called and the network thread allowed to complete before terminating the program. It seems we aren't doing this in all of our bindings, and absent a change to this requirement as proposed in #2978, this can lead to undefined behavior.

It looks like the current state of our in-tree bindings are that:

* Ruby and Python follow the requirements of the API (stop then join)
* Java stops the network thread but doesn't join it
* Go doesn't stop the network thread automatically or provide any API to do it manually as far as I can tell

If #2978 is done, then this won't be an issue. However, I suspect that solving this problem is easier than the other one, so it may be worth updating the two bindings in the meantime.