message: CHANGE: Make `rviz` don't start by default
diff: <arg name="headless" default="false" doc="Should the gazebo GUI be launched?" />
  <arg name="paused" default="false" doc="Should the simulation directly be stopped at 0s?" />
  <arg name="world" default="worlds/empty.world" doc="Filename to a SDF World for gazebo to use" />
  - <arg name="rviz" default="true" doc="Should RVIz be launched?" />
  + <arg name="rviz" default="false" doc="Should RVIz be launched?" />
  <!-- Robot Customization -->
  <arg name="arm_id" default="panda" doc="Name of the panda robot to spawn" />
  