[ROS2] Use relative names for kiss topics

[fdila]

Very minor issue: since the various topics that kiss_icp uses begin with "/" they are absolute, and when running kiss_icp with a specified namespace they don't get remapped.

Allowing namespaces would just be a matter of removing the "/" from the beginning of the name topics here:

kiss-icp/ros/src/OdometryServer.cpp

Lines 115 to 120 in 0395784

	odom_publisher_ = create_publisher<nav_msgs::msg::Odometry>("/kiss/odometry", qos);
	if (publish_debug_clouds_) {
	frame_publisher_ = create_publisher<sensor_msgs::msg::PointCloud2>("/kiss/frame", qos);
	kpoints_publisher_ =
	create_publisher<sensor_msgs::msg::PointCloud2>("/kiss/keypoints", qos);
	map_publisher_ = create_publisher<sensor_msgs::msg::PointCloud2>("/kiss/local_map", qos);

This modification would be beneficial on a multi-robot setup, since using namespaces is pretty much required to run multiple instances of the same node.