fix(tools): close reader when read is completed

close:#1000151163

Signed-off-by: chihe <chihe@oppo.com>
(cherry picked from commit c3b0722c7a)

tool/remotecache-benchmark/main.go

@@ -577,6 +577,7 @@ func (t *BenchmarkTester) runStorageGetBenchmark(ctx context.Context, storage st
 					result.Latencies = append(result.Latencies, latency)
 				}
 				fh.Close()
+				r.Close()
 			}
 		}(w)
 	}