load `streaming=True` dataset with downloaded cache
When you pass `streaming=True`, the cache is ignored. The remote data URL is used instead and the data is streamed from the remote server. Thanks for your reply! So is there any solution to get my expected behavior besides clone the whole repo ? Or could I adjust my script to load the downloaded arrow files and generate the dataset streamingly?
### Describe the bug

We build a dataset which contains several hdf5 files and write a script using `h5py` to generate the dataset. The hdf5 files are large and the processed dataset cache takes more disk space. So we hope to try streaming iterable dataset. Unfortunately, `h5py` can't convert a remote URL into a hdf5 file descriptor. So we use `fsspec` as an interface like below:

```python
def _generate_examples(self, filepath, split):
        for file in filepath:
            with fsspec.open(file, "rb") as fs:
                with h5py.File(fs, "r") as fp:
                    # for event_id in sorted(list(fp.keys())):
                    event_ids = list(fp.keys())
                    ......
```

### Steps to reproduce the bug

The `fsspec` works, but it takes 10+ min to print the first 10 examples, which is even longer than the downloading time. I'm not sure if it just caches the whole hdf5 file and generates the examples.

### Expected behavior

So does the following make sense so far?

1. download the files
```python
dataset = datasets.load('path/to/myscripts', split="train", name="event", trust_remote_code=True)
```

2. load the iterable dataset faster (using the raw file cache at path `.cache/huggingface/datasets/downloads`)
```python
dataset = datasets.load('path/to/myscripts', split="train", name="event", trust_remote_code=True, streaming=true)
```

I made some tests, but the code above can't get the expected result. I'm not sure if this is supported. I also find the issue #6327 . It seemed similar to mine, but I couldn't find a solution.

### Environment info

- `datasets` = 2.18.0
- `h5py` = 3.10.0
- `fsspec` = 2023.10.0