`activation_dropout` in OPT is never used
### System Info

main

### Who can help?

@patil-suraj, @patrickvonplaten, @LysandreJik

### Information

- [X] The official example scripts
- [X] My own modified scripts

### Tasks

- [X] An officially supported task in the `examples` folder (such as GLUE/SQuAD, ...)
- [X] My own task or dataset (give details below)

### Reproduction

https://github.com/huggingface/transformers/blob/ee67e7ad4fd7a766891b68f708cf03e30f609976/src/transformers/models/opt/modeling_opt.py#L279

`activation_dropout` in `modeling_opt.py` is never used. It would not behave as expected if one initial a model randomly while setting it to non-zero.

### Expected behavior

`activation_dropout` is used or removed.
cc @ArthurZucker <|||||>Will have a look asap 😀<|||||>Okay I think we should just remove it, we don't use it in either the flax or the tf version and it is probably a typo. 😄  I will open a PR soon to fix that !<|||||>I'm happy to contribute if removing is what we want 😊<|||||>Feel free to open a PR and tag me when it is ready! 😄 <|||||>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.<|||||>Sorry about the delay! I opened a PR https://github.com/huggingface/transformers/pull/18842 @ArthurZucker <|||||>Gonna merge it to main 🥳 