[refactor] remove conv_cache from CogVideoX VAE (huggingface#9524)

* remove conv cache from the layer and pass as arg instead

* make style

* yiyi's cleaner implementation

Co-Authored-By: YiYi Xu <[email protected]>

* sayak's compiled implementation

Co-Authored-By: Sayak Paul <[email protected]>

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Co-authored-by: Sayak Paul <[email protected]>
Co-authored-by: YiYi Xu <[email protected]>