tests/etcd: remove mod to make test stable (tikv#8102)

ref tikv#7969, close tikv#8091

Signed-off-by: husharp <[email protected]>

pkg/utils/etcdutil/testutil.go

@@ -51,7 +51,7 @@ func NewTestSingleConfig() *embed.Config {
 }
 
 func genRandName() string {
-	return "test_etcd_" + strconv.FormatInt(time.Now().UnixNano()%10000, 10)
+	return "test_etcd_" + strconv.FormatInt(time.Now().UnixNano(), 10)
 }
 
 // NewTestEtcdCluster is used to create a etcd cluster for the unit test purpose.