Minor fixes on the gravity compensation demo package

mode_configs.yaml
- removed

launch script
- removed unused mode configs argument
- removed unused get_interbotix_xsarm_models import

readme
- updated the description about the launch script arguments
- updated the dummy namespace to match the launch script logic: we used the robot name as the namespace

Author: Shiming-Liang

interbotix_ros_xsarms/examples/interbotix_xsarm_gravity_compensation/README.md

@@ -11,15 +11,15 @@ Please refer to the documentations for [`mode_configs`](https://docs.trossenrobo
 
 ## Usage
 
-Run the following launch command where `robot_model` is a mandatory choice between `aloha_wx250s` and `wx250s`, `robot_name` defaults to be the same as `robot_model` but can be anything, `motor_specs` defaults to `<path_to_this_package>/config/motor_specs_<robot_model>.yaml`, and `mode_configs` defaults to `<path_to_this_package>/config/mode_configs_<robot_model>.yaml`:
+Run the following launch command where `robot_model` is a mandatory choice between `aloha_wx250s` and `wx250s`, `robot_name` defaults to be the same as `robot_model` but can be anything, and `motor_specs` defaults to `<path_to_this_package>/config/motor_specs_<robot_model>.yaml`:
 ```
 ros2 launch interbotix_xsarm_gravity_compensation interbotix_gravity_compensation.launch.py robot_model:=xxx [robot_name:=xxx] [motor_specs:=xxx]
 ```
 It runs the `gravity_compensation` node and launches the xsarm_control script to bring up the arm.
 
 Then, enable/disable the gravity compensation with the following service call:
 ```
-ros2 service call /<robot_model>/gravity_compensation_enable std_srvs/srv/SetBool 'data: [true/false]'
+ros2 service call /<robot_name>/gravity_compensation_enable std_srvs/srv/SetBool 'data: [true/false]'
 ```
 
 The arm will hold itself against gravity and can be moved freely when the gravity compensation is enabled.

interbotix_ros_xsarms/examples/interbotix_xsarm_gravity_compensation/config/mode_configs.yaml

@@ -44,8 +44,6 @@
 from launch_ros.actions import Node
 from launch_ros.substitutions import FindPackageShare
 
-from interbotix_xs_modules.xs_common import get_interbotix_xsarm_models
-
 
 def launch_setup(context, *args, **kwargs):
     # Define the launch arguments
@@ -112,16 +110,4 @@ def generate_launch_description():
             description="the file path to the 'motor specs' YAML file.",
         )
     )
-    declared_arguments.append(
-        DeclareLaunchArgument(
-            'mode_configs',
-            default_value=[
-                PathJoinSubstitution([
-                    FindPackageShare('interbotix_xsarm_gravity_compensation'),
-                    'config',
-                    'mode_configs.yaml'])
-            ],
-            description="the file path to the 'mode configs' YAML file.",
-        )
-    )
     return LaunchDescription(declared_arguments + [OpaqueFunction(function=launch_setup)])