insights: remove snapshot/new records from "processing" state

[chwarwick]

The logic that determines if an insight is "Processing" currently takes into account both the backfill record and any snapshots or new recordings queue items. Previously it was not easy to identify if the search job was backfill related or not. This logic remained while we transitioned to the new backfiller.

Remove the job queue record info when determine if a series is "processing" as this is no longer needed, the "Processing" state can now be determined using the backfill record only.

/cc @felixfbecker @vovakulikov