Add a sensor to the WIP code in T412019: [Epic] Schedule scraper and aggregations as an Airflow job, which does the following:

• Check that the scraper job finished successfully, eg. by a scrape >> sensor dependency in the Airflow job.
• Calculate the hour in which the scraper finishes, and add 1 hour.
• Wire this calculated hour from the scraper to the sensor using xcoms.
• Look for an hourly partition on the event.mediawiki_wmde_page_summary table with the form datacenter=eqiad/year=2026/month=1/day=9/hour=23 matching this "hour after success"
• Can use NamedHivePartitionSensor, partition_names_by_granularity with @hourly granularity
• (At this point the page summary data is guaranteed to be complete in Hive.)
• Expect a 3-hour lag between emitting the page summary events to Event Gate through Kafka and Gobblin, until finally persisting in Hive.
• Nice to have: alert if the lag is much longer than 3 hours.