[memory refactor][2/n] Update faiss and make it pass tests (#830)

See https://github.com/meta-llama/llama-stack/issues/827 for the broader
design.

Second part:

- updates routing table / router code 
- updates the faiss implementation


## Test Plan

```
pytest -s -v -k sentence test_vector_io.py --env EMBEDDING_DIMENSION=384
```

tests/client-sdk/conftest.py

@@ -32,6 +32,7 @@ def pytest_addoption(parser):
 TEXT_MODEL = "meta-llama/Llama-3.1-8B-Instruct"
 INFERENCE_MODEL = "meta-llama/Llama-3.2-11B-Vision-Instruct"
 
+
 @pytest.fixture(scope="session")
 def provider_data():
     # check env for tavily secret, brave secret and inject all into provider data