Remove unused pidfd_t member from ThreadHandler

Co-authored-by: clauspruefer <17313789+clauspruefer@users.noreply.github.com>

Author: Copilot

src/ThreadHandler.hpp

@@ -81,7 +81,6 @@ class ThreadHandler
     void _processThreads();
     void _checkProcessed();
 
-    pidfd_t _ParentPidFD;
     ClientRequestDataList_t _RequestsSorted;
     ClientRequestDataListVector_t _ProcessRequests;
     ProcessRequestsIndexList_t _ProcessRequestsIndex;