Perf: reduce upload to minio limiter scope (#7878)

### What problem does this PR solve?
reduce upload_to_minio limter scope

### Type of change
- [x] Performance Improvement

rag/svr/task_executor.py

@@ -277,7 +277,6 @@ async def build_chunks(task, progress_callback):
 
     async def upload_to_minio(document, chunk):
         try:
-            async with minio_limiter:
             d = copy.deepcopy(document)
             d.update(chunk)
             d["id"] = xxhash.xxh64((chunk["content_with_weight"] + str(d["doc_id"])).encode("utf-8")).hexdigest()
@@ -294,8 +293,8 @@ async def build_chunks(task, progress_callback):
                 output_buffer = BytesIO(d["image"])
             else:
                 d["image"].save(output_buffer, format='JPEG')
+            async with minio_limiter:
                 await trio.to_thread.run_sync(lambda: STORAGE_IMPL.put(task["kb_id"], d["id"], output_buffer.getvalue()))
-
             d["img_id"] = "{}-{}".format(task["kb_id"], d["id"])
             del d["image"]
             docs.append(d)