message: [backup] fix backup command in cluster-test
  changed cli command format
  Closes:
  Approved by: andll
diff: @@ -235,6 +235,7 @@ impl PerformanceBenchmark {
  const COMMAND: &str = "while true; do \
  /opt/libra/bin/db-backup one-shot backup \
  --max-chunk-size 1073741824 --backup-service-port 7777 \
  + state-snapshot \
  --state-version $(/opt/libra/bin/db-backup one-shot query --backup-service-port 7777 --latest-version | sed -n 's/latest-version: //p') \
  local-fs --dir $(mktemp -d -t libra_backup_XXXXXXXX); \
  done";
  