[V0 deprecation]clean up is_v1_supported_oracle

[wangxiyuan]

Purpose

Clean up _is_v1_supported_oracle. Let' raise NotImplementedError for unsupported feature directly.

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
• (Optional) The necessary documentation update, such as updating supported_models.md and examples for a new model.
• (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 refactors the engine argument handling to remove the fallback to the V0 engine, which is being deprecated. Instead of falling back, the code now raises a NotImplementedError for unsupported features, making the behavior more explicit and simplifying the codebase. The changes are mainly in vllm/engine/arg_utils.py and the corresponding tests are updated in tests/v1/test_oracle.py. The implementation is sound, but I've found a minor bug in an error message formatting that results in an incomplete message being shown to the user.

[Isotr0py]

LGTM!