Fix bundle_root for NNIGen (#7586)

Fixes #7585  .

### Description

Because the NNI test takes too much time, the previous behavior did not
get caught with the dry-run mode of HPO Gen

### Types of changes
<!--- Put an `x` in all the boxes that apply, and remove the not
applicable items -->
- [x] Non-breaking change (fix or new feature that would not break
existing functionality).

---------

Signed-off-by: Mingxin Zheng <mingxinz@nvidia.com>
Co-authored-by: YunLiu <55491388+KumoLiu@users.noreply.github.com>

Author: mingxin-zheng

monai/apps/auto3dseg/hpo_gen.py

@@ -193,7 +193,9 @@ def generate(self, output_folder: str = ".") -> None:
         self.obj_filename = os.path.join(write_path, "algo_object.pkl")
 
         if isinstance(self.algo, BundleAlgo):
-            self.algo.export_to_disk(output_folder, task_prefix + task_id, fill_with_datastats=False)
+            self.algo.export_to_disk(
+                output_folder, task_prefix + task_id, bundle_root=write_path, fill_with_datastats=False
+            )
         else:
             ConfigParser.export_config_file(self.params, write_path)
             logger.info(write_path)

tests/test_auto3dseg_hpo.py

@@ -181,7 +181,7 @@ def test_get_history(self) -> None:
 
         NNIGen().run_algo(obj_filename, self.work_dir)
         history = import_bundle_algo_history(self.work_dir, only_trained=True)
-        assert len(history) == 3
+        assert len(history) == 1
 
     def tearDown(self) -> None:
         self.test_dir.cleanup()