Make "%LO" and "%LA" more readable when there is only one subclause

Summary:
Depends on D19787. Ref T13217. If we only have one subclause, render WHERE (2 > 1) instead of WHERE ((2 > 1)).

When there are two or more clauses, continue to render WHERE ((2 > 1) AND (3 > 2) AND ...).

Test Plan: Looked at query log in DarkConsole, saw more readable queries.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13217

Differential Revision: https://secure.phabricator.com/D19788