[backport -> release/3.9.x] fix(ai-proxy): fix ai-proxy plugin processing gzip response content l…

[team-gateway-bot]

Automated backport to release/3.9.x, triggered by a label in #13961.

Original description

…enth issue

Summary

When Kong tried to compress the upstream response with gzip in Kong body_filter, the response HTTP header content-length was set to uncompress response content length in header_filter . So kong tells the downstream client HTTP body length bigger than the real content that kong returns. it will let the HTTP client wait some time for data that doesn't exist. So I choose to clear content-length header in the header filter to tell nginx using the chunk transfer encoding method to process the body data.

before:

After:

Checklist

• The Pull Request has tests
• A changelog file has been created under changelog/unreleased/kong or skip-changelog label added on PR if changelog is unnecessary. README.md
• There is a user-facing docs PR against https://github.com/Kong/docs.konghq.com - PUT DOCS PR HERE

Issue reference

Fix AG-182