Test: fix chunk deletion test assertions (#8222)

### What problem does this PR solve?

- Fix test assertions in test_delete_chunks.py to expect empty results
after deletion

Action 7619

### Type of change

- [x] Bug Fix test cases

test/testcases/test_http_api/test_chunk_management_within_dataset/test_delete_chunks.py

         res = list_chunks(HttpApiAuth, dataset_id, document_id)
         if res["code"] != 0:
             assert False, res
-        assert len(res["data"]["chunks"]) == 1
-        assert res["data"]["total"] == 1
+        assert len(res["data"]["chunks"]) == 0
+        assert res["data"]["total"] == 0
 
     @pytest.mark.parametrize(
         "payload, expected_code, expected_message, remaining",