fix thread handler (#2469)

Author: LKuemmel

packages/helpermodules/utils/_thread_handler.py

@@ -27,10 +27,10 @@ def split_chunks(to_split, n):
             thread.start()
 
         # Wait for all to complete
-        for thread in threads_chunk:
+        for thread in threads_to_keep:
             thread.join(timeout=timeout)
 
-        for thread in threads_chunk:
+        for thread in threads_to_keep:
             if thread.is_alive():
                 log.error(f"{thread.name} konnte nicht innerhalb des Timeouts abgearbeitet werden.")
                 not_finished_threads.append(thread.name)