[enhancement] Remove redundant FrankaHWSim panda.launch robot namespace warning

[rickstaa]

When running the roslaunch franka_gazebo panda.launch command, a warning is consistently issued:

Caution: Robot names differ! Read 'arm_id: panda' from the parameter server, but URDF defines '<robotNamespace>/</robotNamespace>'. Will use 'panda'!
This warning is generated by the following code snippet in the franka_hw_sim.cpp file:

franka_ros/franka_gazebo/src/franka_hw_sim.cpp

Lines 39 to 45 in d439fc7

	if (this->arm_id_ != robot_namespace) {
	ROS_WARN_STREAM_NAMED(
	"franka_hw_sim",
	"Caution: Robot names differ! Read 'arm_id: "
	<< this->arm_id_ << "' from parameter server but URDF defines '<robotNamespace>"
	<< robot_namespace << "</robotNamespace>'. Will use '" << this->arm_id_ << "'!");
	}

The intention behind this code was to provide a more explicit warning to users when the robot namespaces don't match, as opposed to the cryptic error message, "Controller Spawner couldn't find the expected controller_manager ROS interface," which occurs when the URDF cannot be loaded (see #187 (comment)).

However, as also pointed out by @gollth in #187 (comment), this issue should no longer be present. The URDF must be successfully located to define the FrankaHWSim plugin, rendering the warning unnecessary.

To address this, I've created PR #366 to remove the code responsible for generating this warning.

TODOs

• merge refactor(franka_gazebo): remove FrankaHWSim robot namespace warning #366.