http_client output parameter "drop_on" is confusing

[choult]

The labelling of the http_client output parameter drop_on is confusing, as the message is not dropped but instead attempts to complete delivery via the output itself is aborted. This can lead to a difficult-to-reason-about infinite loop as the message can then make it back into the head of the pipeline and back into the same output.

Consider renaming the parameter abort_on so that it's more clear that the message itself is not dropped.