state_history_plugin unused code

[heifner]

libraries/state_history/include/eosio/state_history/log.hpp state_history_log The internal thread is not used.

   std::thread                                                              thr;
   std::atomic<bool>                                                        write_thread_has_exception = false;
   std::exception_ptr                                                       eptr;
   boost::asio::io_context                                                  ctx;
   boost::asio::io_context::strand                                          work_strand{ctx};
   boost::asio::executor_work_guard<boost::asio::io_context::executor_type> work_guard =
       boost::asio::make_work_guard(ctx);
   std::recursive_mutex                                                     mx;

The thr and ctx is not used for anything after creation. The mx is not protecting anything that needs protection.

[stephenpdeos]

Closing based off above references