add benchmark flag to backup creation for proper cleanup when running a benchmark

Signed-off-by: Hannes Laimer <h.laimer@proxmox.com>
Signed-off-by: Dietmar Maurer <dietmar@proxmox.com>

src/bin/proxmox_backup_client/benchmark.rs

@@ -226,6 +226,7 @@ async fn test_upload_speed(
         "benchmark",
         backup_time,
         false,
+        true
     ).await?;
 
     if verbose { eprintln!("Start TLS speed test"); }