etcdctl: remove SetConsistency call

This call to SetConsistency is explicitly setting the default
value, so it's really unnecessary.

etcdctl/command/exec_watch_command.go

@@ -65,7 +65,6 @@ func execWatchCommandFunc(c *cli.Context, client *etcd.Client) (*etcd.Response,
 	}()
 
 	receiver := make(chan *etcd.Response)
-	client.SetConsistency(etcd.STRONG_CONSISTENCY)
 	go client.Watch(key, uint64(index), recursive, receiver, stop)
 
 	for {