Fixes #5692: Update send_clean.sh to meet quality standards

Ticket: http://www.rudder-project.org/redmine/issues/5692

To be merged in 3.0
Can you please add the name of the inventory handled? This will make it possible to relate this warning message to an actual file.

Also, please add this sentence: "This often happens due to rate-throttling in the endpoint to save on memory consumption. This is standard behavior."