torchbench_model.py: fix YAML skip file path (#6457)
This fixes the following error, caught by yesterday's nightly run:
```
$ cd pytorch
$ python xla/benchmarks/experiment_runner.py --test=eval --test=train --xla=PJRT --dynamo=None --dynamo=openxla --dynamo=openxla_eval --suite-name=torchbench --accelerator=cuda --output-dirname=/tmp/foo --repeat=8 --print-subprocess --timestamp=1706835612
[...]
Traceback (most recent call last):
File "/home/ecg/nightly_runs/2024-02-02/pytorch/xla/benchmarks/experiment_runner.py", line 908, in <module>
main()
File "/home/ecg/nightly_runs/2024-02-02/pytorch/xla/benchmarks/experiment_runner.py", line 903, in main
runner = ExperimentRunner(args)
File "/home/ecg/nightly_runs/2024-02-02/pytorch/xla/benchmarks/experiment_runner.py", line 41, in __init__
self.model_loader = TorchBenchModelLoader(self._args)
File "/home/ecg/nightly_runs/2024-02-02/pytorch/xla/benchmarks/torchbench_model.py", line 160, in __init__
self.skip = self.get_skip_data()
File "/home/ecg/nightly_runs/2024-02-02/pytorch/xla/benchmarks/torchbench_model.py", line 202, in get_skip_data
with open(skip_file) as f:
FileNotFoundError: [Errno 2] No such file or directory: '/home/ecg/nightly_runs/2024-02-02/pytorch/benchmarks/dynamo/dynamo/torchbench_skip_models.yaml'
```
