fix(response-ratelimiting): fix missing usage headers for upstream

[t-yuki]

Summary

response-ratelimiting plugin should send usage headers to upstream server.
But in Kong 3.8, there are no usage headers such as X-RateLimit-Remaining-Videos: 10 for upstream requests.

In this change, it coming back usage headers for upstream.

Checklist

• The Pull Request has tests
  • It seems to be already there are tests for this feature but are there passing? https://github.com/Kong/kong/blob/master/spec/03-plugins/24-response-rate-limiting/04-access_spec.lua#L505
• 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 #13682

[ADD-SP]

@t-yuki Thanks for your contribution! Would you mind adding a regression test on this issue? I think we have missed this test for a long time.

And also a changelog entry.

[ADD-SP]

Since this is a new issue introduced in 3.8 and should be a small fix, I added this to the 3.9 milestone.

Internal ticket: KAG-5447

[ADD-SP]

@t-yuki Could you fix failure tests?

[t-yuki]

@t-yuki Could you fix failure tests?

OK, I'll try to continue within a week.

[gszr]

Since this is touching a recent nontrivial refactor, we should carefully verify it doesn't revert important bits of said refactor, fixing one but introducing other issues. cc @ADD-SP

[ADD-SP]

Approved to run CIs against https://github.com/Kong/kong/pull/13696/files/b98da5efa4c8a70cb05725b9ea09c5ff680c8170.

[ADD-SP]

CI is not started 🤔, no idea about the reason yet.

[ADD-SP]

@t-yuki Thanks for your contribution!