Better log message needed when updating an existing collection record

[jkeifer]

Updating a collection record via ingest currently produces an error log message that seems to indicate that something went wrong. That message is like {"level":"error","message":"$COLLECTION already exists."}. I believe to most people this message would indicate that the update failed, but that is not the case.

The message is emitted here. It indicates that the index for a given collection already exists and thus there is no attempt to create it. I do not believe this case to be an error, but more informational or perhaps even debug-level. I also think the message is problematically vague, and should be explicit like "index for collection {} already exists, skipping creation".