fix(pathfinder/sync/transactions): fix transaction sync

[kkovaacs]

This PR fixes a few unrelated issues in transaction sync:

• queries returning counts from the block header now return data in-order in a VecDeque
• "counts" streams now pop the next element off of the front of the queue
• "counts" streams now properly yield all elements from the last chunk
• SQL query for transaction counts / commitments contained a syntax error
• peer_agnostic::Client::transaction_stream() should handle FIN as the stream termination, not as a block separator