Bug: benchmarks/transactions-generator benchmark report more transactions processed than injected

[ssavenko-near]

Which network are you using?

other (specify below)
commit ccf16b5. The earlier versions have this issue too.

What happened?

Running the benchmarks/transactions-generator just do-it 20000 reports more transactions processed than injected.
master.log

2025-03-17T14:38:14.269995Z  INFO transaction-generator: total="Stats { pool_accepted: 899896, pool_rejected: 100, processed: 1429436, failed: 0 }"
2025-03-17T14:38:14.270004Z  INFO transaction-generator: diff="Stats { pool_accepted: 10000, pool_rejected: 0, processed: 19620, failed: 0 }" rate_processed=15702
...
2025-03-17T14:38:38.269588Z  INFO transaction-generator: total="Stats { pool_accepted: 1058929, pool_rejected: 80297, processed: 1796840, failed: 0 }"
2025-03-17T14:38:38.269595Z  INFO transaction-generator: diff="Stats { pool_accepted: 0, pool_rejected: 9230, processed: 0, failed: 0 }" rate_processed=15624

The neard before separating the tx processing and chunk production (see the branch) exhibits the same behavior but the diff is smaller

tx-mult.log

2025-03-17T13:46:14.740272Z  INFO transaction-generator: total="Stats { pool_accepted: 1176419, pool_rejected: 100, processed: 1276906, failed: 0 }"
2025-03-17T13:46:14.740298Z  INFO transaction-generator: diff="Stats { pool_accepted: 3837, pool_rejected: 0, processed: 1314, failed: 0 }" rate_processed=7470

Running the benchmark with a lower rate (~4k TPS) does not reproduce the issue.

Relevant log output

2025-03-17T14:38:14.269995Z  INFO transaction-generator: total="Stats { pool_accepted: 899896, pool_rejected: 100, processed: 1429436, failed: 0 }"
2025-03-17T14:38:14.270004Z  INFO transaction-generator: diff="Stats { pool_accepted: 10000, pool_rejected: 0, processed: 19620, failed: 0 }" rate_processed=15702