unused import [2/n] (meta-pytorch#3416)

Summary:
Pull Request resolved: meta-pytorch#3416

https://www.flake8rules.com/rules/F401.html

Reviewed By: TroyGarden

Differential Revision: D83739245

fbshipit-source-id: f7418dc140d9ae00ffc3fe134e5f02d7ee213e09

Author: aliafzal

torchrec/distributed/benchmark/benchmark_train_pipeline.py

@@ -21,21 +21,16 @@
 """
 
 from dataclasses import dataclass, field
-from typing import Dict, List, Optional, Type, Union
+from typing import Dict, List, Optional, Type
 
 import torch
 from fbgemm_gpu.split_embedding_configs import EmbOptimType
 from torch import nn
 from torchrec.distributed.benchmark.benchmark_pipeline_utils import (
     BaseModelConfig,
     create_model_config,
-    DeepFMConfig,
-    DLRMConfig,
     generate_data,
     generate_pipeline,
-    TestSparseNNConfig,
-    TestTowerCollectionSparseNNConfig,
-    TestTowerSparseNNConfig,
 )
 from torchrec.distributed.benchmark.benchmark_utils import (
     benchmark_func,