community: replace deprecated davinci models (#14860)

This is technically a breaking change because it'll switch out default
models from `text-davinci-003` to `gpt-3.5-turbo-instruct`, but OpenAI
is shutting off those endpoints on 1/4 anyways.

Feels less disruptive to switch out the default instead.

libs/community/tests/integration_tests/llms/test_openai.py

@@ -50,7 +50,7 @@ def test_openai_extra_kwargs() -> None:
 
     # Test that "model" cannot be specified in kwargs
     with pytest.raises(ValueError):
-        OpenAI(model_kwargs={"model": "text-davinci-003"})
+        OpenAI(model_kwargs={"model": "gpt-3.5-turbo-instruct"})
 
 
 def test_openai_llm_output_contains_model_name() -> None:
@@ -286,7 +286,7 @@ def mock_completion() -> dict:
         "id": "cmpl-3evkmQda5Hu7fcZavknQda3SQ",
         "object": "text_completion",
         "created": 1689989000,
-        "model": "text-davinci-003",
+        "model": "gpt-3.5-turbo-instruct",
         "choices": [
             {"text": "Bar Baz", "index": 0, "logprobs": None, "finish_reason": "length"}
         ],