Fix CI test StorageClient.url_preparator
Fix CI test StorageClient.url_preparator.

This fail in CI tests was introduced after:
- #2966

See: https://github.com/huggingface/dataset-viewer/actions/runs/10350752694/job/28648303009?pr=3018
```
FAILED tests/test_response.py::test_create_response_with_image - AssertionError: assert [{'row': {'im...d_cells': []}] == [{'row': {'im...d_cells': []}]
  
  At index 0 diff: {'row_idx': 0, 'row': {'image': {'src': 'http://localhost/cached-assets/ds_image/--/{dataset_git_revision}/--/default/train/0/image/image.jpg', 'height': 480, 'width': 640}}, 'truncated_cells': []} != {'row_idx': 0, 'row': {'image': {'src': 'http://localhost/cached-assets/ds_image/--/revision/--/default/train/0/image/image.jpg', 'height': 480, 'width': 640}}, 'truncated_cells': []}
  
  Full diff:
    [
        {
            'row': {
                'image': {
                    'height': 480,
  -                 'src': 'http://localhost/cached-assets/ds_image/--/revision/--/default/train/0/image/image.jpg',
  +                 'src': 'http://localhost/cached-assets/ds_image/--/{dataset_git_revision}/--/default/train/0/image/image.jpg',
  ?                                                                    +++++++++++++        +
                    'width': 640,
                },
            },
            'row_idx': 0,
            'truncated_cells': [],
        },
    ]
```
Fix CI test StorageClient.url_preparator: Fix CI test StorageClient.url_preparator.

This fail in CI tests was introduced after:
- #2966

See: https://github.com/huggingface/dataset-viewer/actions/runs/10350752694/job/28648303009?pr=3018
```
FAILED tests/test_response.py::test_create_response_with_image - AssertionError: assert [{'row': {'im...d_cells': []}] == [{'row': {'im...d_cells': []}]
  
  At index 0 diff: {'row_idx': 0, 'row': {'image': {'src': 'http://localhost/cached-assets/ds_image/--/{dataset_git_revision}/--/default/train/0/image/image.jpg', 'height': 480, 'width': 640}}, 'truncated_cells': []} != {'row_idx': 0, 'row': {'image': {'src': 'http://localhost/cached-assets/ds_image/--/revision/--/default/train/0/image/image.jpg', 'height': 480, 'width': 640}}, 'truncated_cells': []}
  
  Full diff:
    [
        {
            'row': {
                'image': {
                    'height': 480,
  -                 'src': 'http://localhost/cached-assets/ds_image/--/revision/--/default/train/0/image/image.jpg',
  +                 'src': 'http://localhost/cached-assets/ds_image/--/{dataset_git_revision}/--/default/train/0/image/image.jpg',
  ?                                                                    +++++++++++++        +
                    'width': 640,
                },
            },
            'row_idx': 0,
            'truncated_cells': [],
        },
    ]
```