feat(ai-proxy): add telemetry for ai-proxy

[tysoekong]

Summary

Adds telemetry for AI/LLM "model" and "provider" usage.

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 request.

[team-gateway-bot]

Successfully created backport PR for release/3.6.x:

• [backport -> release/3.6.x] feat(ai-proxy): add telemetry for ai-proxy #12495

[team-gateway-bot]

Backport failed for release/3.6.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/3.6.x
git worktree add -d .worktree/backport-12492-to-release/3.6.x origin/release/3.6.x
cd .worktree/backport-12492-to-release/3.6.x
git switch --create backport-12492-to-release/3.6.x
git cherry-pick -x 00211cbe328d10831b0940b21e6d35ed0b880268

[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-12492-to-master-to-upstream upstream/master
cd .worktree/cherry-pick-12492-to-master-to-upstream
git checkout -b cherry-pick-12492-to-master-to-upstream
ancref=$(git merge-base c7cb900f4919e6b320b7bdf9132cfa4747679760 bfa2c9eec1420426c2841e6a30f0f67fc924fb4c)
git cherry-pick -x $ancref..bfa2c9eec1420426c2841e6a30f0f67fc924fb4c

[team-gateway-bot]

Backport failed for release/3.6.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/3.6.x
git worktree add -d .worktree/backport-12492-to-release/3.6.x origin/release/3.6.x
cd .worktree/backport-12492-to-release/3.6.x
git switch --create backport-12492-to-release/3.6.x
git cherry-pick -x 00211cbe328d10831b0940b21e6d35ed0b880268

[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-12492-to-master-to-upstream upstream/master
cd .worktree/cherry-pick-12492-to-master-to-upstream
git checkout -b cherry-pick-12492-to-master-to-upstream
ancref=$(git merge-base c7cb900f4919e6b320b7bdf9132cfa4747679760 bfa2c9eec1420426c2841e6a30f0f67fc924fb4c)
git cherry-pick -x $ancref..bfa2c9eec1420426c2841e6a30f0f67fc924fb4c

[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-12492-to-master-to-upstream upstream/master
cd .worktree/cherry-pick-12492-to-master-to-upstream
git checkout -b cherry-pick-12492-to-master-to-upstream
ancref=$(git merge-base c7cb900f4919e6b320b7bdf9132cfa4747679760 bfa2c9eec1420426c2841e6a30f0f67fc924fb4c)
git cherry-pick -x $ancref..bfa2c9eec1420426c2841e6a30f0f67fc924fb4c