Remove padding_masks from `gpt_bigcode`.
Author: susnato
Pull request: yes

# What does this PR do?

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This PR removes `padding_masks` from gpt bigcode as [discussed](https://github.com/huggingface/transformers/pull/26486#issuecomment-1798466670) here.


## Before submitting
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Models:

- text models: @ArthurZucker and @younesbelkada
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Library:

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cc: @amyeroberts 


Comments:
The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_27348). All of your documentation changes will be reflected on that endpoint.