TAJO-910: Simple query (non-forwarded query) should be supported against partition tables.

It may be the number of rows. I have a suggestion. In my view, ```fetch.row-num``` is more intuitive.  ```fetch.size``` is relatively mis-understandable, and it seems to be the number of bytes rather than the number of rows. It's because we have used ```size``` prefix for the number of bytes in many config keys.