message: validation: put coins cache write log into bench debug log
diff: @@ -2017,8 +2017,8 @@ bool CChainState::FlushStateToDisk(
  }
  // Flush best chain related state. This can only be done if the blocks / block index write was also done.
  if (fDoFullFlush && !CoinsTip().GetBestBlock().IsNull()) {
  - LOG_TIME_SECONDS(strprintf("write coins cache to disk (%d coins, %.2fkB)",
  - coins_count, coins_mem_usage / 1000));
  + LOG_TIME_MILLIS_WITH_CATEGORY(strprintf("write coins cache to disk (%d coins, %.2fkB)",
  + coins_count, coins_mem_usage / 1000), BCLog::BENCH);
  // Typical Coin structures on disk are around 48 bytes in size.
  // Pushing a new one to the database can cause it to be written
  