When the sync queue processes results for a blocks by range request,
and the requested range contained some slots that are already finalized,
`BlockError.MissingParent` currently leads to `PeerScoreBadBlocks` even
when the error occurs on a non-finalized slot in the requested range.
This patch changes the scoring in that case to `PeerScoreMissingBlocks`
for consistency with range requests solely covering non-finalized slots,
and, likewise, rewinds the sync queue to the next `rewindSlot`.
3ba016d75f