fuzz: Stop nodes in process_message* fuzzers

src/test/fuzz/process_messages.cpp

@@ -75,6 +75,7 @@ void test_one_input(const std::vector<uint8_t>& buffer)
         } catch (const std::ios_base::failure&) {
         }
     }
-    connman.ClearTestNodes();
     SyncWithValidationInterfaceQueue();
+    LOCK2(::cs_main, g_cs_orphans); // See init.cpp for rationale for implicit locking order requirement
+    g_setup->m_node.connman->StopNodes();
 }