Pass onnx model output directly to post_inference request handler

[vishalbollu]

Closes #

---

Checklist:

• Run make test and make lint
• Test end to end manually (e.g. build/push all images, restart operator, and run cx refresh)
• Update examples
• Update documentation (add any new files to summary.md)
• Merge to master
• Cherry-pick into release branches if it's a bugfix
• Check gitbook that docs look good and links function properly
• Alert team if dev environment changed
• Delete the branch once it's merged