revert(map_loader): revert the change error handling when pcd_metadata file (#6294)

Revert "fix(map_loader): change error handling when pcd_metadata file not found (#6227)"

This reverts commit 25bc636.

Author: SakodaShintaro

map/map_loader/src/pointcloud_map_loader/pointcloud_map_loader_node.cpp

@@ -90,9 +90,8 @@ std::map<std::string, PCDFileMetadata> PointCloudMapLoaderNode::getPCDMetadata(
 {
   std::map<std::string, PCDFileMetadata> pcd_metadata_dict;
   if (pcd_paths.size() != 1) {
-    while (!fs::exists(pcd_metadata_path)) {
-      RCLCPP_ERROR_STREAM(get_logger(), "PCD metadata file not found: " << pcd_metadata_path);
-      std::this_thread::sleep_for(std::chrono::seconds(1));
+    if (!fs::exists(pcd_metadata_path)) {
+      throw std::runtime_error("PCD metadata file not found: " + pcd_metadata_path);
     }
 
     pcd_metadata_dict = loadPCDMetadata(pcd_metadata_path);