[WIP] AIP-89 Privacy-first telemetry

Motivation

Currently, Airflow uses Scarf for telemetry collection, which has raised several concerns:

1. Privacy and GDPR compliance issues, particularly around data collection consent
2. Limited transparency about what data is collected and how it's used
3. Lack of user control over what information is shared
4. Corporate users face challenges with enabling telemetry due to internal policies

However, telemetry data is crucial for Airflow's development:

1. Understanding how features are used helps prioritize development efforts
2. Error reports help identify and fix issues more quickly
3. Usage patterns inform API design and deprecation decisions
4. Performance metrics guide optimization efforts

The current situation has led to lower telemetry adoption, reducing the insights available to maintainers while also potentially creating privacy risks for users who do enable telemetry.