webrequest: analyzer: don't trigger alerts check.
email alerts are generated but not delivered for now.
The send_alerts task must not have a parent in the execution
sequence. Otherwise, airflow will trying to execute it right away
and get stuck retrying on failure (partitions with no email alerts).
Alerts will still be generated by the WebrequestMetrics spark job,
and stored in wmf_data_ops.data_quality_alerts.
Bug: T349763