Reduce rpc test code (#9413)

automerge

cli/src/test_utils.rs

@@ -0,0 +1,16 @@
+use solana_client::rpc_client::RpcClient;
+use solana_sdk::pubkey::Pubkey;
+use std::{thread::sleep, time::Duration};
+
+pub fn check_balance(expected_balance: u64, client: &RpcClient, pubkey: &Pubkey) {
+    (0..5).for_each(|tries| {
+        let balance = client.retry_get_balance(pubkey, 1).unwrap().unwrap();
+        if balance == expected_balance {
+            return;
+        }
+        if tries == 4 {
+            assert_eq!(balance, expected_balance);
+        }
+        sleep(Duration::from_millis(500));
+    });
+}