Fix get_unacked_iterator (#6280)

### What problem does this PR solve?

Fix get_unacked_iterator. Close #6132 

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)

rag/svr/task_executor.py

     global DONE_TASKS, FAILED_TASKS
     redis_msg, task = await collect()
     if not task:
+        await trio.sleep(5)
         return
     try:
         logging.info(f"handle_task begin for task {json.dumps(task)}")

rag/utils/redis_conn.py

         """https://redis.io/docs/latest/commands/xreadgroup/"""
         try:
             group_info = self.REDIS.xinfo_groups(queue_name)
-            if not any(e["name"] == group_name for e in group_info):
+            if not any(gi["name"] == group_name for gi in group_info):
                 self.REDIS.xgroup_create(queue_name, group_name, id="0", mkstream=True)
             args = {
                 "groupname": group_name,
             res = RedisMsg(self.REDIS, queue_name, group_name, msg_id, payload)
             return res
         except Exception as e:
-            if "key" in str(e):
+            if str(e) == 'no such key':
                 pass
             else:
                 logging.exception(
     def get_unacked_iterator(self, queue_names: list[str], group_name, consumer_name):
         try:
             for queue_name in queue_names:
-                group_info = self.REDIS.xinfo_groups(queue_name)
-                if not any(e["name"] == group_name for e in group_info):
+                try:
+                    group_info = self.REDIS.xinfo_groups(queue_name)
+                except Exception as e:
+                    if str(e) == 'no such key':
+                        logging.warning(f"RedisDB.get_unacked_iterator queue {queue_name} doesn't exist")
+                        continue
+                if not any(gi["name"] == group_name for gi in group_info):
+                    logging.warning(f"RedisDB.get_unacked_iterator queue {queue_name} group {group_name} doesn't exist")
                     continue
                 current_min = 0
                 while True:
                     if not payload:
                         break
                     current_min = payload.get_msg_id()
-                    logging.info(f"RedisDB.get_unacked_iterator {consumer_name} msg_id {current_min}")
+                    logging.info(f"RedisDB.get_unacked_iterator {queue_name} {consumer_name} {current_min}")
                     yield payload
-        except Exception as e:
-            if "key" in str(e):
-                return
+        except Exception:
             logging.exception(
-                "RedisDB.get_unacked_iterator " + consumer_name + " got exception: "
+                "RedisDB.get_unacked_iterator got exception: "
             )
             self.__open__()