fix: azure openai api key not picking up env var (#13267)

...-azure-openai/llama_index/embeddings/azure_openai/base.py

...ddings/llama-index-embeddings-azure-openai/pyproject.toml

...-index-embeddings-azure-openai/tests/test_azure_openai.py

...x-llms-azure-openai/llama_index/llms/azure_openai/base.py

...rations/llms/llama-index-llms-azure-openai/pyproject.toml

.../llama-index-llms-azure-openai/tests/test_azure_openai.py