ReshardingOplogFetcher starts with 0 delay but will start having the default 1s delay on subsequent getMores unconditionally. We should keep the delay to 0s as long as we had items on the last batch and only set the delay value if last batch returned empty. This adds unnecessary pause between each getMores, the only case where we should add a delay is when there are no new oplog and we don't want to spam the donor.