[Hubs] Fail ingestion when older than the retention period

📝 Scenario

As a FinOps hub admin, I need to fail data ingestion when a month that is older than the data retention period is attempted to be ingested in order to clarify why ingested data is not available

💎 Solution

In the ingestion_ExecuteETL pipeline, check if the ingested month is older than the final data retention. If older, then fail the pipeline run with a clear error that states the data is older than the data retention and add documentation to indicate that they need to update the final retention period.

📋 Tasks

### Required tasks
- [ ] Update ingestion_ExecuteETL to fail if ingested data is older than configured retention
- [ ] Document the error code and how to resolve it
- [ ] Document the scenario in the troubleshooting guide

### Stretch goals
- [ ] TODO: Add tasks

🙋‍♀️ 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.

Start by locating the ingestion_ExecuteETL pipeline and the configured final data retention setting, then inspect the existing ingestion error handling and troubleshooting guide. The work is done when older months fail with a clear error, the error code and retention-period resolution are documented, and the scenario appears in the troubleshooting guide.