fix(ai-proxy): prevent shared state

[Tieske]

The object initializer (new) would set properties on class instead of on the instance. Also cleans up some code.

I have added comments on the actual bug, everything else is cosmetic/cleanup. Please review with whitespace changes disabled in the github UI.

Summary

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

Internal ticket: AG-44

[Tieske]

Comment to reviewers: self was pointing to _M in the old code. So setting self.conf, self.http_opts, and self.driver would actually modify the class, and not the instance.

[Tieske]

Comment to reviewers: The old code would call on llm (the class) instead of on ai_driver (the instance).

[Tieske]

Comment to reviewers: The old code would call on llm (the class) instead of on ai_driver (the instance).

[subnetmarco]

Are there any more changes requested on this PR? @Tieske @liverpool8056

[fffonion]

Probably out scope of this PR, but just want to share for visibility: using of kong.ctx.shared.X to shared between plugins is
not very robust way as a single typo in the variable name X would cause logic to fail silently. Especially when the ai plugins
have lots of branchs and not easy to cover all in tests.
Ideally they should also be moved to a proper function call like llm.state.getX() llm.state.setX() as then a typo will cause a hard failure in error log. I started a small refactor of this as part of this PR 9f511ab.
After seeing this PR, it might make sense to let the kong.llm.state module store things in the instance (is it per request?).

[Tieske]

@fffonion I think that makes sense as a follow up. For now, I think we should merge this as is.

[outsinre]

Approve with minor suggestion.

[team-gateway-bot]

Cherry-pick failed for master, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally.

git remote add upstream https://github.com/kong/kong-ee
git fetch upstream master
git worktree add -d .worktree/cherry-pick-13028-to-master-to-upstream upstream/master
cd .worktree/cherry-pick-13028-to-master-to-upstream
git checkout -b cherry-pick-13028-to-master-to-upstream
ancref=$(git merge-base 3df996a3ac14f38ba9e9d354aea37f1a08f530b9 ed0b56680cb0ec2eb9c264b34525f6ce30a07cb5)
git cherry-pick -x $ancref..ed0b56680cb0ec2eb9c264b34525f6ce30a07cb5

[team-gateway-bot]

Backport failed for release/3.7.x, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally and resolve any conflicts.

git fetch origin release/3.7.x
git worktree add -d .worktree/backport-13028-to-release/3.7.x origin/release/3.7.x
cd .worktree/backport-13028-to-release/3.7.x
git switch --create backport-13028-to-release/3.7.x
git cherry-pick -x 18a189baff77ed23a32ec7a01d45d116aa6d6fce

[team-gateway-bot]

Cherry-pick failed for master, because it was unable to cherry-pick the commit(s).

Please cherry-pick the changes locally.

git remote add upstream https://github.com/kong/kong-ee
git fetch upstream master
git worktree add -d .worktree/cherry-pick-13028-to-master-to-upstream upstream/master
cd .worktree/cherry-pick-13028-to-master-to-upstream
git checkout -b cherry-pick-13028-to-master-to-upstream
ancref=$(git merge-base 3df996a3ac14f38ba9e9d354aea37f1a08f530b9 ed0b56680cb0ec2eb9c264b34525f6ce30a07cb5)
git cherry-pick -x $ancref..ed0b56680cb0ec2eb9c264b34525f6ce30a07cb5

[AndyZhang0707]

Hi @Tieske , the auto backport and cherry-pick failed, could you please manually create the backport and cherry-pick PRs? Thanks.