Flaky Unit Test test_rpc_subscriptions (#27214)

Increase unit test timeout from 5 seconds to 10 seconds

rpc-test/tests/rpc.rs

@@ -402,7 +402,7 @@ fn test_rpc_subscriptions() {
         }
     }
 
-    let deadline = Instant::now() + Duration::from_secs(5);
+    let deadline = Instant::now() + Duration::from_secs(10);
     let mut account_notifications = transactions.len();
     while account_notifications > 0 {
         let timeout = deadline.saturating_duration_since(Instant::now());