Added False case implementation for config.do_stable_layer_norm in FlaxWav2vec2Models
Author: ctr-pmuruganTT
Pull request: yes
Labels: name: Flax

# What does this PR do?

In [FlaxWa2Vec2](https://github.com/huggingface/transformers/blob/397a5ede33863d6f7137c771a68d40036cac0396/src/transformers/models/wav2vec2/modeling_flax_wav2vec2.py#L953) there is no implementation when `config.do_stable_layer_norm` is false. 

There are more chances that we will get this Not Implemented error frequently, since this value is false by default. 

For this scenario, there is an implementation in [modeling_tf_wav2vec2.py](https://github.com/huggingface/transformers/blob/397a5ede33863d6f7137c771a68d40036cac0396/src/transformers/models/wav2vec2/modeling_tf_wav2vec2.py#L1195). I have recreated the same in flax version for `modeling_flax_wav2vec2.py`

I have added 4  functions which are the No Stable Layer version code for existing functions

* FlaxWav2Vec2LayerNormPostAttention                           -> FlaxWav2Vec2StableLayerNormEncoder
* FlaxWav2Vec2LayerNormPostAttentionCollection          -> FlaxWav2Vec2EncoderLayerStableLayerNormCollection
* FlaxWav2Vec2EncoderStableLayerNormPostAttention  -> FlaxWav2Vec2EncoderLayerStableLayerNorm
* FlaxWav2Vec2NoLayerNormConvLayer                           -> FlaxWav2Vec2LayerNormConvLayer


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Fixes https://github.com/huggingface/transformers/issues/37731



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Attaching some Screenshots for reference :

### Before making this change, I am getting the error as stated in #37731 

![Screenshot 2025-04-28 at 10 11 04 AM](https://github.com/user-attachments/assets/d094546b-d01e-48bc-bb5a-d40ed3bd1021)

### After making this change, Model is loaded and I am able to print it 

![Screenshot 2025-04-28 at 10 28 47 AM](https://github.com/user-attachments/assets/d553b3e6-d033-490a-bb4f-b45633e8d722)



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Comments:
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Hi @ctr-pmuruganTT 👋  Thank you for opening the PR

FYI `flax`+`transformers` is in support mode, and we're usually not adding PRs that go beyond a few LoC. My recommendation would be for you to keep a fork of `transformers`, with your changes on top :)

>FYI `flax`+`transformers` is in support mode, and we're usually not adding PRs that go beyond a few LoC

Hi @gante, does this mean that for any future model no JAX implementations will be added in `transformers` library nor accepted as external contribution? I'm curious if you could please share any more details regarding this.

Yeah :) That has been the state for FLAX in `transformers` for like 2 years

(TL;DR maintaining different ML frameworks is very costly, and FLAX/TF has very low usage compared to torch)

I understand, thank you for the info @gante! I've noticed there haven't been many updates to the Flax models, and I guessed it has something to do with your prioritization, but I wasn't aware you also wouldn't be open to external contributions in that space :) I can understand though, it takes time from someone on your side to review/maintain the changes.

@ctr-pmuruganTT let's keep these changes on a branch and we will see how to port them to our repo, this PR can be closed

For the aforementioned reasons, closing this PR 🤗