What's changing

Since the inference job was created which has support for running the OpenAI and Mistral completion service, the /completions route is duplicating effort and increasing the complexity of the codebase. Lumigator is now designed to be an evaluation platform, not a proxy to other LLMs.

With this in mind, this PR deletes the completion route: inference with OpenAI and Mistral is still supported via running the inference job, so this PR does not remove functionilty, but rather consolidates our LLM inference logic into a single location (the inference job)

How to test it

The SDK had a connection to the completions/ route but the frontend didn't so the functionality appears to be unused. Unit tests and integration tests passing seem like enough, as long as we all agree on removing it.

I already...

• Tested the changes in a working environment to ensure they work as expected
• Added some tests for any new functionality
• Updated the documentation (both comments in code and product documentation under /docs)
• Checked if a (backend) DB migration step was required and included it if required