Best Practices & Analysis Summary Report - Warning about Expensive Events on system_health session.

[asavioliMSFT]

Currently we give an alert in case we find expensive extended events being collected on SQL, like statement level events, wait_info etc. We are giving this warning even for Microsoft owned system events, like the system_health.

We could add an exclusion for system extended events or add a column indicating this is a system session, not one created by the user

[hacitandogan]

fix is under #381 and will be merged, closing this.