fix(api): 修正retriever_resources字段的处理逻辑。fixes #<14650>

[liguochuan00]

Summary

When querying historical message data using the messages interface, it is found that the return field retrieverResources is [] anyway. So I want to submit a PR to fix this problem. fixes #<14650>

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Checklist

[!IMPORTANT]
Please review the checklist below before submitting your pull request.

• [ ] This change requires a documentation update, included: Dify Document
• [x] I understand that this PR may be closed in case there was no previous discussion or issues. (This doesn't apply to typos!)
• [x] I've added a test for each change that was introduced, and I tried as much as possible to make a single atomic change.
• [x] I've updated the documentation accordingly.
• [x] I ran dev/reformat(backend) and cd web && npx lint-staged(frontend) to appease the lint gods

[liguochuan00]

I fixed the issues 14650, please review it as soon as possible.

[liguochuan00]

Do I need to revise it? I think you have made corresponding changes

[crazywoola]

Do I need to revise it? I think you have made corresponding changes

Yes, however it introduced a non-existing method to it. So you still need to fix it I think.

[liguochuan00]

Please take a look at the bot's review, and run dev/reformat to resolve lint errors. What does this mean? How should I implement it

[liguochuan00]

I resubmitted