Exception on saving results in official glue example scripts
### System Info

- `transformers` version: 4.25.0.dev0
- Platform: Linux-4.14.81.bm.22-amd64-x86_64-with-glibc2.17
- Python version: 3.8.13
- Huggingface_hub version: 0.10.0
- PyTorch version (GPU?): 1.12.1+cu116 (True)
- Tensorflow version (GPU?): not installed (NA)
- Flax version (CPU?/GPU?/TPU?): not installed (NA)
- Jax version: not installed
- JaxLib version: not installed
- Using GPU in script?: yes
- Using distributed or parallel set-up in script?: no

### Who can help?

@sgugger, @patil-suraj 

### 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

I was running the official glue example script `transformers/examples/pytorch/text-classification/run_glue_no_trainer.py` on STS-B task. 

```sh
export TASK_NAME=stsb
python run_glue_no_trainer.py \
  --model_name_or_path bert-base-cased \
  --task_name $TASK_NAME \
  --max_length 128 \
  --per_device_train_batch_size 32 \
  --learning_rate 2e-5 \
  --num_train_epochs 3 \
  --output_dir /tmp/$TASK_NAME/
```

The training went well, but on saving the results it raised the error below:

```
Configuration saved in /tmp/stsb/config.json
Model weights saved in /tmp/stsb/pytorch_model.bin
tokenizer config file saved in /tmp/stsb/tokenizer_config.json
Special tokens file saved in /tmp/stsb/special_tokens_map.json
Traceback (most recent call last):
  File "run_glue_no_trainer.py", line 633, in <module>
    main()
  File "run_glue_no_trainer.py", line 629, in main
    json.dump({"eval_accuracy": eval_metric["accuracy"]}, f)
KeyError: 'accuracy'
```


### Expected behavior

Some of the glue tasks (STS-B, CoLA) don't use "accuracy" as metric. Maybe need to check the metric keys before accessing `eval_metric`.

https://github.com/huggingface/transformers/blob/504db92e7da010070c36e185332420a1d52c12b2/examples/pytorch/text-classification/run_glue_no_trainer.py#L627-L629

BTW, I have noticed that this block of code also appears in lots of other example scripts like multiple-choice, semantic-segmentation, etc. I'm not sure whether those scripts have the same issue.

Yes, the whole `eval_metric` dict should probably be dumped without accessing keys. Do you want to open a PR with this change?
cc @muellerzr who wrote this.<|||||>Yeah, I'd like to help. The `eval_metric` should be dumped with all its keys prefixed by `eval_`, just like what `run_glue.py` does.
https://github.com/huggingface/transformers/blob/504db92e7da010070c36e185332420a1d52c12b2/examples/pytorch/text-classification/run_glue.py#L573

I happen to find an example script that already fixed this issue by prefixing all keys in `eval_metric` before saving it.
https://github.com/huggingface/transformers/blob/6cc06d17394f5715cdf2d13a1ef7680bedaee9e2/examples/pytorch/question-answering/run_qa_beam_search_no_trainer.py#L66-L86

 I will create a PR to migrate this solution to all remaining unfixed examples. Is it ok?<|||||>That would be great, yeah!