[BE][Easy][3/19] enforce style for empty lines in import segments in benchmarks/ (#129754)

See https://github.com/pytorch/pytorch/pull/129751#issue-2380881501. Most changes are auto-generated by linter.

You can review these PRs via:

```bash
git diff --ignore-all-space --ignore-blank-lines HEAD~1
```

Pull Request resolved: https://github.com/pytorch/pytorch/pull/129754
Approved by: https://github.com/ezyang

benchmarks/transformer/better_transformer_vs_mha_functional.py

@@ -12,7 +12,6 @@ import argparse
 import itertools
 import json
 import random
-
 import warnings
 from collections import defaultdict, OrderedDict
 from pathlib import Path
@@ -20,12 +19,12 @@ from pprint import pprint
 from typing import Optional
 
 import numpy as np
-
 from prettytable import PrettyTable
 from tqdm import tqdm
 
 import torch
 
+
 warnings.filterwarnings("ignore")
 
 error_dict = defaultdict(int)

benchmarks/transformer/score_mod.py

@@ -13,6 +13,7 @@ import torch
 import torch.nn.functional as F
 from torch.nn.attention.flex_attention import flex_attention
 
+
 torch._dynamo.config.automatic_dynamic_shapes = False
 # Needed since changing args to function causes recompiles
 torch._dynamo.config.cache_size_limit = 1000

benchmarks/transformer/sdp.py

@@ -1,7 +1,6 @@
 import argparse
 import itertools
 import random
-
 import warnings
 from dataclasses import dataclass
 from pathlib import Path
@@ -16,6 +15,7 @@ import torch
 import torch.utils.benchmark as benchmark
 from torch.backends.cuda import sdp_kernel
 
+
 warnings.filterwarnings("ignore")