Better defaults for remote.yaml

- Use `text-embedding-3-small` instead of ADA for embeddings; as shown in our retrieval benchmark, the improvement in quality is very significant.
- Use `gpt-4o` instead of `gpt4`. According to OpenAI, it's cheaper and better.

sage/configs/remote.yaml

@@ -1,6 +1,6 @@
 # Embeddings
 embedding-provider: openai
-embedding-model: text-embedding-ada-002
+embedding-model: text-embedding-3-small
 tokens-per-chunk: 800
 chunks-per-batch: 2000
 
@@ -11,7 +11,7 @@ hybrid-retrieval: true
 
 # LLM
 llm-provider: openai
-llm-model: gpt-4
+llm-model: gpt-4o
 
 # Reranking
-reranker-provider: nvidia
+reranker-provider: nvidia