fix actix-pg benchmark (#3995)

frameworks/Rust/actix/src/main_pg.rs

@@ -147,7 +147,6 @@ fn main() {
     }).backlog(8192)
         .bind("0.0.0.0:8080")
         .unwrap()
-        .workers(1)
         .start();
 
     println!("Started http server: 127.0.0.1:8080");

frameworks/Rust/actix/src/main_raw.rs

@@ -271,7 +271,7 @@ fn main() {
     HttpServer::new(move || {
         let dbs = Rc::new(RefCell::new(Vec::new()));
 
-        for _ in 0..3 {
+        for _ in 0..2 {
             let db = dbs.clone();
             Arbiter::spawn(
                 PgConnection::connect(db_url)