[`Vision-Encoder- Decoder`] Add `vision-encoder-decoder` on `AutoProcessor`
# What does this PR do?

Similarly as https://github.com/huggingface/transformers/pull/21319 & #21299 a doctest was failing because the correct processor was not mapped in the `AutoProcessor` mapping for `vision-encoder-decoder`

This fixes also a doctest that was failing, link to failing job: https://github.com/huggingface/transformers/actions/runs/4002271138/jobs/6869333719 

cc @ydshieh @sgugger 
See https://github.com/huggingface/transformers/pull/21319#issuecomment-1404938821<|||||>Closing in favor of opening PRs on the Hub as described in the comment! <|||||>The docs for this PR live [here](https://moon-ci-docs.huggingface.co/docs/transformers/pr_21320). All of your documentation changes will be reflected on that endpoint.