[Hubs] Don't ingest empty files

[flanakin]

🐛 Problem

The ingestion_ExecuteETL pipeline triggers ingestion_ETL_dataExplorer when there are no rows.

👣 Repro steps

1. Export data for a period which has no data (e.g., transactions on the first of the month)
2. The ingestion_ExecuteETL pipeline will trigger the ingestion_ETL_dataExplorer pipeline for a single file with no rows, which will fail to ingest because there are no rows

🤔 Expected

Nothing should be ingested when there are no rows. There should be no errors.

ℹ️ Additional context

Update the ingestion_ExecuteETL pipeline to check the export manifest.json file for the "dataRowCount" integer JSON property. If the value is 0, do not try to ingest data. If we fail to read the value, continue to ingest the data assuming there is at least one row.

🙋‍♀️ Ask for the community

We could use your help:

1. Please vote this issue up (👍) to prioritize it.
2. Leave comments to help us solidify the vision.

[bmargula]

This has also totally confused me the last days and I can confirm this issue and would vote for it to be fixed.

[MSBrett]

This issue specifies the solution design for the bug reported in #1535.

[japyjaap]

Just did a multi tenant installation (8 tenants). most tenants are new, so no reservations or recommendation data. The daily ingestion process takes more than 10 hours due to the export files with 0 lines being processed. Definitely would vote for adding the check for "dataRowCount"=0.