fix: make task cancellation non-blocking consistent with Redis fire-and-forget pattern

Author: Algorithm5838

backend/open_webui/tasks.py

@@ -155,17 +155,8 @@ async def stop_task(redis, task_id: str):
     if not task:
         return {"status": False, "message": f"Task with ID {task_id} not found."}
 
-    task.cancel()  # Request task cancellation
-    try:
-        await task  # Wait for the task to handle the cancellation
-    except asyncio.CancelledError:
-        # Task successfully canceled
-        return {"status": True, "message": f"Task {task_id} successfully stopped."}
-
-    if task.cancelled() or task.done():
-        return {"status": True, "message": f"Task {task_id} successfully cancelled."}
-
-    return {"status": True, "message": f"Cancellation requested for {task_id}."}
+    task.cancel()
+    return {"status": True, "message": f"Task {task_id} cancellation requested."}
 
 
 async def stop_item_tasks(redis: Redis, item_id: str):