Fix #1600

Removed unnecessary `` which cause problems with pgsql.
https://github.com/mybb/mybb/issues/1600
@Sama34, first of all, I don't think you understand the term 'spaghetti code'. It's something hard to read and understand by others, not something inconsistent. Removing an useless brace and concatenation doesn't make it more difficult for anyone, do they for you?

As an example, this random line could be considered a bit spaghetti:
https://github.com/mybb/mybb/blob/feature/forumdisplay.php#L159
since it can be simplified to this ' ' syntax:
https://github.com/Sama34/mybb/commit/04f5ced45c435cb1cbfa2ad263dd2e6058797bca#diff-c6480c1a3fe8c1a339ac23fcdc05d97dR2555
The 1st ugly version is used almost everywhere in core, does that mean you wrote spaghetti code by not sticking to it?

Another example - Euan used `try ... catch` in this PR:
https://github.com/mybb/mybb/pull/928
Not used often (if at all) in the core either, but does that mean it's bad? I guess not, since (let me quote your comment there):
> That is, an interesting and different coding style btw.

Also, as others have said above, it's used in other places in core too. Sometimes the whole query is even in one line, even though it could be divided into multiple.

Lastly, since you failed to show me which standard is not followed by me, I end my discussion on that matter here (and any other similar in the future). Thank you and have fun.