max_execution_speed setting does not work if SAMPLE is used

CC @zhang2014 

```
example.yandex.ru :) SET max_execution_speed = 1000000

SET max_execution_speed = 1000000

Ok.

0 rows in set. Elapsed: 0.001 sec. 

example.yandex.ru :) SELECT ...

1 rows in set. Elapsed: 10.360 sec. Processed 318.26 million rows, 57.65 GB (30.72 million rows/s., 5.56 GB/s.)
```