adds flag to disable duplicate instance check (#15006)

core/tests/gossip.rs

@@ -25,8 +25,14 @@ fn test_node(exit: &Arc<AtomicBool>) -> (Arc<ClusterInfo>, GossipService, UdpSoc
     let keypair = Arc::new(Keypair::new());
     let mut test_node = Node::new_localhost_with_pubkey(&keypair.pubkey());
     let cluster_info = Arc::new(ClusterInfo::new(test_node.info.clone(), keypair));
-    let gossip_service =
-        GossipService::new(&cluster_info, None, test_node.sockets.gossip, None, exit);
+    let gossip_service = GossipService::new(
+        &cluster_info,
+        None,
+        test_node.sockets.gossip,
+        None,
+        true, // should_check_duplicate_instance
+        exit,
+    );
     let _ = cluster_info.my_contact_info();
     (
         cluster_info,
@@ -47,6 +53,7 @@ fn test_node_with_bank(
         Some(bank_forks),
         test_node.sockets.gossip,
         None,
+        true, // should_check_duplicate_instance
         exit,
     );
     let _ = cluster_info.my_contact_info();