[Backend] Maybe go back to previous embedding function

Did it run locally ?

With openai embeddings you could get :
```
Retrying langchain.embeddings.openai.embed_with_retry.._embed_with_retry in 4.0 seconds as it raised
APIConnectionError: Error communicating with OpenAI: HTTPSConnectionPool(host='api.openai.com', port=443): Max retries
exceeded with url: /v1/embeddings (Caused by NameResolutionError(": Failed to resolve 'api.openai.com' ([Errno -3] Temporary failure in name resolution)")).
```