fuzz: set fSuccessfullyConnected in connman harness

Without this, NodeFullyConnected() filters out every fuzz-constructed node, making ForEachNode's callback unreachable (0/1.13M branch hits from my end).

src/test/fuzz/connman.cpp

@@ -89,6 +89,8 @@ FUZZ_TARGET(connman, .init = initialize_connman)
 
     LIMITED_WHILE(fuzzed_data_provider.ConsumeBool(), 100) {
         CNode& p2p_node{*ConsumeNodeAsUniquePtr(fuzzed_data_provider).release()};
+        // Simulate post-handshake state.
+        p2p_node.fSuccessfullyConnected = true;
         connman.AddTestNode(p2p_node);
     }