Use config limit instead of default (#20900) (#20906)

(cherry picked from commit 9dd87bcdb5)

Co-authored-by: Tyera Eulberg <teulberg@gmail.com>

rpc/src/rpc_subscriptions.rs

@@ -505,7 +505,7 @@ impl RpcSubscriptions {
             .unwrap();
 
         let control = SubscriptionControl::new(
-            PubSubConfig::default().max_active_subscriptions,
+            config.max_active_subscriptions,
             notification_sender.clone(),
             broadcast_sender,
         );