improve function calling check for legacy openai agents (#17015)

...lama_index/agent/openai_legacy/context_retriever_agent.py

...ions/agent/llama-index-agent-openai-legacy/pyproject.toml

.../llama-index-llms-openai/llama_index/llms/openai/utils.py

...-integrations/llms/llama-index-llms-openai/pyproject.toml