implement per-thread, per-batch sleep in ms (throttling allows easier UI dev) (#2293)

* implement per-thread, per-batch sleep in ms (throttling allows easier UI development)
* tidy up sleep() call with Duration::from_millis() instead of Duration::new()
* fixup indentation style
* removing multinode-demo/client-throttled.sh (same functionality available via arguments)

bench-tps/src/main.rs

@@ -82,6 +82,7 @@ fn main() {
         drone_addr,
         id,
         threads,
+        thread_batch_sleep_ms,
         num_nodes,
         duration,
         tx_count,
@@ -207,6 +208,7 @@ fn main() {
                         &leader,
                         &shared_tx_active_thread_count,
                         &total_tx_sent_count,
+                        thread_batch_sleep_ms,
                     );
                 })
                 .unwrap()