[skip ci] Delete unused package of client on benchmark (#12853)

Signed-off-by: wangting0128 <ting.wang@zilliz.com>

tests/benchmark/milvus_benchmark/client.py

@@ -4,7 +4,6 @@ import time
 import traceback
 from multiprocessing import Process
 from pymilvus import Milvus, DataType
-import numpy as np
 import utils as util
 import config
 from milvus_benchmark.runners import utils