Fix bank coalescing (#949)

* fix bank coalescing

* comments

* fix bench

* fix bench

* backout banking stage coalescing

* 120 nodes

* 100

tests/multinode.rs

@@ -524,7 +524,7 @@ fn test_multi_node_dynamic_network() {
         Ok(val) => val
             .parse()
             .expect(&format!("env var {} is not parse-able as usize", key)),
-        Err(_) => 230,
+        Err(_) => 100,
     };
 
     let purge_key = "SOLANA_DYNAMIC_NODES_PURGE_LAG";