OPAL should inform user if Fetcher returns extremely large value.

[avo-sepp]

Is your feature request related to a problem? Please describe. When OPAL receives a very large input from a fetcher, the OPA/OPAL pod tends to crash and restart automatically. This isn't clear to the user, and was leading me to look for problems in the wrong places.

Describe the solution you'd like If there was a warning in the logs, or even just information, about the size of the data fetched. It could be a warning that the data size is over some limit. Or it could just be information about the size of the data ingested. Or perhaps if the OPA pod crashes after ingesting data, the message is somehow clearer that the pod crashed due to memory error. This would help when debugging data ingestion failure.