verify gemma 2b and add sample script

[Sunjnn]

verify gemma 2b and add sample script

在 MACA 平台测试 vllm 是否能够运行 gemma 2b.

离线运行和在线运行均可.

离线运行结果:

在线运行结果:

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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.

[gemini-code-assist]

Code Review

This pull request adds support for the Gemma 2 9B model by including a new example script and updating the list of supported models. The documentation update is correct. However, the new example script docs/models/samples/gemma2_9b.py uses trust_remote_code=True, which introduces a critical security vulnerability by allowing arbitrary code execution. I've added a comment to highlight this issue and suggest adding a clear warning to users in the example script.