Revert "Refa: make RAGFlow more asynchronous 2 (#11664)"

This reverts commit 627c11c429.

api/db/services/document_service.py

@@ -719,14 +719,10 @@ class DocumentService(CommonService):
                 # only for special task and parsed docs and unfinished
                 freeze_progress = special_task_running and doc_progress >= 1 and not finished
                 msg = "\n".join(sorted(msg))
-                begin_at = d.get("process_begin_at")
-                if not begin_at:
-                    begin_at = datetime.now()
-                    # fallback
-                    cls.update_by_id(d["id"], {"process_begin_at": begin_at})
-
                 info = {
-                    "process_duration": max(datetime.timestamp(datetime.now()) - begin_at.timestamp(), 0),
+                    "process_duration": datetime.timestamp(
+                        datetime.now()) -
+                                       d["process_begin_at"].timestamp(),
                     "run": status}
                 if prg != 0 and not freeze_progress:
                     info["progress"] = prg