Suppress warning when using `DataCollatorForSeq2Seq`
### Feature request

When using a fast tokenizer in the `DataCollatorForSeq2Seq`, currently the following warning is printed 

```
You're using a T5TokenizerFast tokenizer. Please note that with a fast tokenizer, using the `__call__` method is faster than using a method to encode the text followed by a call to the `pad` method to get a padded encoding.
```

As a temporary solution, what is the suggested way to suppress it?

Is there any plan to update `DataCollatorForSeq2Seq`?

Thanks a lot in advance for your help!

### Motivation

N/A

### Your contribution

N/A
cc @sgugger <|||||>Could you post a clear reproducer of the issue? Thanks a lot!<|||||>This issue has been automatically marked as stale because it has not had recent activity. If you think this still needs to be addressed please comment on this thread.

Please note that issues that do not follow the [contributing guidelines](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md) are likely to be ignored.<|||||>> Could you post a clear reproducer of the issue? Thanks a lot!

When fine tuning a DialoGPT-medium model with a custom Dataset class as so:

```
class ConversationDataset(Dataset):
    def __init__(self, tokenizer, file_path, block_size):
        self.tokenizer = tokenizer
        self.block_size = block_size
        self.inputs = []
        self.responses = []

        with open(file_path, 'r', encoding="utf-8") as file:
            lines = file.readlines()
            for i in range(0, len(lines), 2):
                if i + 1 < len(lines):
                    self.inputs.append(lines[i].strip().replace("input: ", ""))
                    self.responses.append(lines[i + 1].strip().replace("response: ", ""))

        # Tokenize and pad inputs and responses in a single step
        self.input_tensors = tokenizer(self.inputs, return_tensors='pt', padding=True, truncation=True, max_length=self.block_size)
        self.response_tensors = tokenizer(self.responses, return_tensors='pt', padding=True, truncation=True, max_length=self.block_size)
```<|||||>This is being fixed by #23742