Fix DAM Unit Test

nvflare/app_opt/xgboost/histogram_based_v2/__init__.py

@@ -11,6 +11,3 @@
 # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 # See the License for the specific language governing permissions and
 # limitations under the License.
-
-from nvflare.app_opt.xgboost.histogram_based_v2.fed_controller import XGBFedController
-from nvflare.app_opt.xgboost.histogram_based_v2.fed_executor import FedXGBHistogramExecutor