Refactor QueuedBlocks and SentHashes fields on StateService to avoid unnecessary utxo removals and re-additions

[arya2]

Motivation

In PR #5257 known_utxos of queued blocks were added to the sent hashes when blocks are dequeued and sent to the block write task. Removing the UTXOs from QueuedBlocks and re-adding them to SentHashes can be easily avoided by coupling QueuedBlocks and SentHashes together.

See #5339

[teor2345]

Thanks for opening this ticket!

I'm going to mark it as "not scheduled", because we're not doing changes this large while the audit is pending.

Feel free to re-open it if it's needed for other work, or after the audit fixes are complete.