How to use keyless auth (managed identity) for AzureOpenAIVectorizerParameters in integrated vectorization notebook?

Hi team,

I'm trying to use the notebook at:

[azure-search-integrated-vectorization-sample.ipynb](https://github.com/Azure/azure-search-vector-samples/blob/main/demo-python/code/integrated-vectorization/azure-search-integrated-vectorization-sample.ipynb)

In the vector search configuration section, the AzureOpenAIVectorizerParameters currently requires an api_key:

`# Configure the vector search configuration
vector_search = VectorSearch(
algorithms=[
HnswAlgorithmConfiguration(name="myHnsw"),
],
profiles=[
VectorSearchProfile(
name="myHnswProfile",
algorithm_configuration_name="myHnsw",
vectorizer_name="myOpenAI",
)
],
vectorizers=[
AzureOpenAIVectorizer(
vectorizer_name="myOpenAI",
kind="azureOpenAI",
parameters=AzureOpenAIVectorizerParameters(
resource_url=azure_openai_endpoint,
deployment_name=azure_openai_embedding_deployment,
model_name=azure_openai_model_name,
api_key=azure_openai_key,
),
),
],
) `

Is there currently a way to use keyless authentication (e.g., system-assigned managed identity) instead of providing an api_key in AzureOpenAIVectorizerParameters?

If not:
Is this a planned feature?
Is there a recommended workaround for now?

Start with azure-search-integrated-vectorization-sample.ipynb and its AzureOpenAIVectorizerParameters configuration. Check the current Azure AI Search and Azure OpenAI authentication support for managed identities, then review the sample's vector search setup and determine whether the notebook can document or demonstrate keyless authentication. Done means the supported approach, planned status, or limitation is clear.

Written by the indexing model from the issue text.