Usage analytics: detect "AIRFLOW_HOME" env var as signal for Airflow-managed runtimes

We should stay on top of how many users are leveraging Airflow as a runtime for PyAirbyte so that we can make intelligent decisions around support and prioritization for those use cases.

A straightforward way to do this would be to detect the presence of the `AIRFLOW_HOME` env var, or a similar signal.

https://airflow.apache.org/docs/apache-airflow/stable/start/local.html#setting-the-airflow-home-location

Cc @bindipankhudi