Fix idempotency issue for network modules. (#32838)

After the connection refactor if response value returned from
the remote device is empty in that case an `ok` return value is send
to module side code. To avoid this do not overwrite the empty response
received from remote device in `jsonrpc` reply.

lib/ansible/utils/jsonrpc.py

@@ -83,7 +83,7 @@ class JsonRpcServer(object):
 
     def response(self, result=None):
         response = self.header()
-        response['result'] = result or 'ok'
+        response['result'] = result
         return response
 
     def error(self, code, message, data=None):