message: fix joint state names for grippers
diff: <param name="publish_default_efforts" value="False" />
  <rosparam param="source_list">[panda_left_state_controller/joint_states,
  panda_right_state_controller/joint_states,
  - panda_left_gripper_node/joint_states,
  - panda_right_gripper_node/joint_states]
  + panda_left/franka_gripper/joint_states,
  + panda_right/franka_gripper/joint_states]
  </rosparam>
  <param name="rate" value="30"/>
  </node>
  