almost all codes that related to generation in examples/pytorch/**_no_trainer.py have bugs
Author: Namco0816
Pull request: no
Labels: name: bug

### System Info

```shell
transformers branch main
```


### Wrong Codes in examples/pytorch/**_no_trainer.py

```
for step, batch in enumerate(eval_dataloader):
            with torch.no_grad():
                generated_tokens = accelerator.unwrap_model(model).generate(
                    batch["input_ids"],
                    attention_mask=batch["attention_mask"],
                    **gen_kwargs,
                )

                generated_tokens = accelerator.pad_across_processes(
                    generated_tokens, dim=1, pad_index=tokenizer.pad_token_id
                )
                labels = batch["labels"]
                if not args.pad_to_max_length:
                    # If we did not pad to max length, we need to pad the labels too
                    labels = accelerator.pad_across_processes(batch["labels"], dim=1, pad_index=tokenizer.pad_token_id)

                generated_tokens, labels = accelerator.gather((generated_tokens, labels))
                generated_tokens = generated_tokens.cpu().numpy()
                labels = labels.cpu().numpy()

                if args.ignore_pad_token_for_loss:
                    # Replace -100 in the labels as we can't decode them.
                    labels = np.where(labels != -100, labels, tokenizer.pad_token_id)
                if isinstance(generated_tokens, tuple):
                    generated_tokens = generated_tokens[0]
                decoded_preds = tokenizer.batch_decode(generated_tokens, skip_special_tokens=True)
                decoded_labels = tokenizer.batch_decode(labels, skip_special_tokens=True)

                decoded_preds, decoded_labels = postprocess_text(decoded_preds, decoded_labels)
                # If we are in a multiprocess environment, the last batch has duplicates
                if accelerator.num_processes > 1:
                    if step == len(eval_dataloader):
                        decoded_preds = decoded_preds[: len(eval_dataloader.dataset) - samples_seen]
                        decoded_labels = decoded_labels[: len(eval_dataloader.dataset) - samples_seen]
                    else:
                        samples_seen += decoded_labels.shape[0]
```

here, In the for loop, step will never equal to len(eval_dataloader), so here should be modified to `if step == len(eval_dataloader) - 1`

and

`samples_seen += decoded_labels.shape[0]`

decoded_labels is a list that produced by the postprocess_text(),
list object have no attribute shape.

GLHF

### Information

- [X] The official example scripts
- [ ] My own modified scripts

### Tasks

- [X] An officially supported task in the `examples` folder (such as GLUE/SQuAD, ...)
- [ ] My own task or dataset (give details below)

### Reproduction

just run the examples scripts provided in the readme

### Expected behavior

```shell
samples_seen exceed the dataset size
and also the attribute error
```


Comments:
I believe that's in @muellerzr's todo list!

Yes it is, duplicate of https://github.com/huggingface/transformers/issues/17214#event-6600140325

Will be getting to this on Wednesday once I'm back from vacation