[Misc] Add removed encoder-decoder models to previously supported models list

[Isotr0py]

Purpose

• Following PR for Remove V0 Encoder-Decoder Support #24907, so that users can get clear messages about models deprecation in new version.

Test Plan

Test Result

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Essential Elements of an Effective PR Description Checklist

• The purpose of the PR, such as "Fix some issue (link existing issues this PR will resolve)".
• The test plan, such as providing test command.
• The test results, such as pasting the results comparison before and after, or e2e results
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• (Optional) Release notes update. If your change is user facing, please update the release notes draft in the Google Doc.

[gemini-code-assist]

Code Review

This pull request adds several recently removed encoder-decoder models to the _PREVIOUSLY_SUPPORTED_MODELS list. This is a good change as it will provide users with a clear and helpful deprecation message if they attempt to use these models, improving the overall user experience. The implementation is straightforward and correct. I have no major concerns with this change.

[DarkLight1337]

Thanks!

[vrdn-23]

@Isotr0py @DarkLight1337 Does this mean there will be a temporary period of not supporting these models or are these encoder-decoder models not going to supported going forward in vLLM?

Apologies if I missed this, but was there an online discussion that kind of highlighted the reasons for the deprecation of these models?

[DarkLight1337]

We have decided to drop all encoder-decoder models except for Whisper to avoid code complexity in the model runner. #23300 (comment)