fix(reranker): support omitting top_n

[mkhludnev]

Description

This PR fixes the issue introduced in #7025

Notes for Reviewers

#7025 introduced handling result cropping by top_n. However, I believe the most users just omit top_n, just because don't bother to count len(documents). So, I'm afraid releasing #7025 causes a trouble for many users. @mudler, beg your pardon.
This PR let users to omit top_n or send top_n=0 meaning all docs.

One thing about tests, since tey bring up the backend every time, isn't it worth to loop three alt requests in the single test method?

Signed commits

• [v] Yes, I signed my commits.

[netlify]

✅ Deploy Preview for localai ready!

Name	Link
🔨 Latest commit	eec1f59
🔍 Latest deploy log	https://app.netlify.com/projects/localai/deploys/6910b05b2fe2450008889c8d
😎 Deploy Preview	https://deploy-preview-7199--localai.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify project configuration.

[mkhludnev]

otherwise we can better handle top_n REST API param

notice https://api.jina.ai/redoc#tag/rerank/operation/rank_v1_rerank_post

defaults to the length of documents

[mudler]

#7025 introduced handling result cropping by top_n. However, I believe the most users just omit top_n, just because don't bother to count len(documents). So, I'm afraid releasing #7025 causes a trouble for many users. @mudler, beg your pardon. This PR let users to omit top_n or send top_n=0 meaning all docs.

One thing about tests, since tey bring up the backend every time, isn't it worth to loop three alt requests in the single test method?

Yes, that would make def. sense!

[mudler]

Thanks for following up!

[mkhludnev]

asserts #7284