use cend for consistency

Author: jncfa

rclcpp/executors/multithreaded_executor/multithreaded_executor.cpp

@@ -32,7 +32,7 @@ std::string string_thread_id()
   static std::vector<std::thread::id> known_thread_ids {};
   const auto thread_it = std::find(known_thread_ids.cbegin(), known_thread_ids.cend(),
     std::this_thread::get_id());
-  if (thread_it != known_thread_ids.end()) {
+  if (thread_it != known_thread_ids.cend()) {
     return std::to_string(std::distance(known_thread_ids.cbegin(), thread_it));
   }
   known_thread_ids.push_back(std::this_thread::get_id());