Remove misleading TODO

This TDOO is misleading, because - to our current knowledge - it is impossible for
Bob to retrieve the exact inclusion block-height of the lock transaction (send by Alice).
The wallet RPC is only capable of retrieving the inclusion block height of a transaction
through `get_payments` and `get_bulk_payments` which requires the `payment_id`.
The `payment_id` can be retrieved through `get_transfer_by_txid` which states
"Show information about a transfer to/from this address." - however the address that the
transfer goes to is not part of Bob's wallet yet! Thus, it is impossible for Bob to use
`get_transfer_by_txid` which in turn means Bob is unable to use `get_payments`.

The only possible way for Bob to know the exact inclusion block/height of the lock transaction
would be if Alice sends it over to Bob. But for that Alice would have to extract it she would have
to wait for confirmation - which she currently does not and might never do. Even if she does await
the first confirmation before sending the transfer proof the solution for retrieving the inclusion
block-height is not fleshed out on her side yet.

swap/src/protocol/bob/swap.rs

@@ -129,9 +129,6 @@ async fn run_until_internal(
 
                     // Record the current monero wallet block height so we don't have to scan from
                     // block 0 once we create the redeem wallet.
-                    // TODO: This can be optimized further by extracting the block height when
-                    //  tx-lock was included. However, scanning a few more blocks won't do any harm
-                    //  and is simpler.
                     let monero_wallet_restore_blockheight = monero_wallet.block_height().await?;
 
                     select! {