Add warning message for beta and gamma parameters
Author: OmarManzoor
Pull request: yes

# What does this PR do?
This adds a warning message to notify about the renaming of `gamma` and `beta` parameters during initialisation and also during loading.

<!--
Congratulations! You've made it this far! You're not quite done yet though.

Once merged, your PR is going to appear in the release notes with the title you set, so make sure it's a great title that fully reflects the extent of your awesome contribution.

Then, please replace this with a description of the change and which issue is fixed (if applicable). Please also include relevant motivation and context. List any dependencies (if any) that are required for this change.

Once you're done, someone will review your PR shortly (see the section "Who can review?" below to tag some potential reviewers). They may suggest changes to make the code even better. If no one reviewed your PR after a week has passed, don't hesitate to post a new comment @-mentioning the same persons---sometimes notifications get lost.
-->

<!-- Remove if not applicable -->

Fixes #29554


## Before submitting
- [x] Did you read the [contributor guideline](https://github.com/huggingface/transformers/blob/main/CONTRIBUTING.md#create-a-pull-request),
      Pull Request section?
- [x] Was this discussed/approved via a Github issue or the [forum](https://discuss.huggingface.co/)? Please add a link
      to it if that's the case.
- [X] Did you write any new necessary tests?


## Who can review?

@amyeroberts 

<!-- Your PR will be replied to more quickly if you can figure out the right person to tag with @

 If you know how to use git blame, that is the easiest way, otherwise, here is a rough guide of **who to tag**.
 Please tag fewer than 3 people.

Models:

- text models: @ArthurZucker
- vision models: @amyeroberts
- speech models: @sanchit-gandhi
- graph models: @clefourrier

Library:

- flax: @sanchit-gandhi
- generate: @zucchini-nlp (visual-language models) or @gante (all others)
- pipelines: @Narsil
- tensorflow: @gante and @Rocketknight1
- tokenizers: @ArthurZucker
- trainer: @muellerzr and @SunMarc

Integrations:

- deepspeed: HF Trainer/Accelerate: @muellerzr
- ray/raytune: @richardliaw, @amogkam
- Big Model Inference: @SunMarc
- quantization (bitsandbytes, autogpt): @SunMarc 

Documentation: @stevhliu and @MKhalusova

HF projects:

- accelerate: [different repo](https://github.com/huggingface/accelerate)
- datasets: [different repo](https://github.com/huggingface/datasets)
- diffusers: [different repo](https://github.com/huggingface/diffusers)
- rust tokenizers: [different repo](https://github.com/huggingface/tokenizers)

Maintained examples (not research project or legacy):

- Flax: @sanchit-gandhi
- PyTorch: See Models above and tag the person corresponding to the modality of the example.
- TensorFlow: @Rocketknight1

 -->


Comments:
> Hi @OmarManzoor,
> 
> Thanks for addressing this! We want to make sure we catch any place where the renaming happens, so any place where `if gamma in key` and `if beta in key` are True (so key can be a longer string that contains beta or gamma). As you've added, this would be in `_load_pretrained_model` but also in [_load_state_dict_into_model](https://github.com/huggingface/transformers/blob/e65502951593a76844e872fee9c56b805598538a/src/transformers/modeling_utils.py#L662)

Hi @amyeroberts 
Thanks for the feedback. Should we remove it during initialization? I added it in post init because during the main init we might not have the parameters declared.

>> Given the diff, I'm slightly confused, were there no warnings being triggered before? It seems like they were from the tests and logging messages

I basically removed the warning code that I added in the post init method. Should that be kept?

@OmarManzoor Ah, OK. I think the diff was rendering funny on github. Should be OK. 

> Looks great - thanks for adding and iterating on this!

Thank you.

Why have you added warnings only for the initialization process and not for renaming during loading as well? The model I'm using is timm's convnext (which is even the companion framework to transformers), which would have the parameter gamma. When loading he just tells me that I didn't successfully load the gamma function without telling me why, and I think the user should be informed when renaming the state_dict, otherwise it will cause unnecessary confusion.