[SQL] Kill dangerous trailing space in query string

MD5 of query strings in `createQueryTest` calls are used to generate golden files, leaving trailing spaces there can be really dangerous. Got bitten by this while working on #2616: my "smart" IDE automatically removed a trailing space and makes Jenkins fail.

(Really should add "no trailing space" to our coding style guidelines!)

Author: Cheng Lian <lian.cs.zju@gmail.com>

Closes #2619 from liancheng/kill-trailing-space and squashes the following commits:

034f119 [Cheng Lian] Kill dangerous trailing space in query string