insights: fixed insight data series global only flag fetching the appropriate series

Created by: coury-clark

Fixes a bug that would only appear if the condition for the GlobalOnly predicate was compounded with another predicate due to order of operations. This bug caused some series to endlessly backfill despite already having backfill_completed_at set to non-null.

Also taking a chance to remove / lower the log level of some really noisy logs.