chore(autoware_pointcloud_preprocessor): change unnecessary warning message to debug (autowarefoundation#8525) (#1590)

Co-authored-by: Yi-Hsiang Fang (Vivid) <146902905+vividf@users.noreply.github.com>

Author: h-ohta

sensing/pointcloud_preprocessor/src/concatenate_data/concatenate_and_time_sync_nodelet.cpp

@@ -286,7 +286,7 @@ PointCloudConcatenateDataSynchronizerComponent::computeTransformToAdjustForOldTi
 
   // return identity if old_stamp is newer than new_stamp
   if (old_stamp > new_stamp) {
-    RCLCPP_WARN_STREAM_THROTTLE(
+    RCLCPP_DEBUG_STREAM_THROTTLE(
       get_logger(), *get_clock(), std::chrono::milliseconds(10000).count(),
       "old_stamp is newer than new_stamp,");
     return Eigen::Matrix4f::Identity();