LEFT JOIN instead of JOIN for ApplicationSearch ordering

Summary: Ref T4659. Because we JOIN, tasks with no value are filtered out. Instead, LEFT JOIN.

Test Plan: Issued an "Order by" and got all applicable tasks. Adjusted values and saw order change.

Reviewers: btrahan, hach-que

Reviewed By: hach-que

Subscribers: epriestley

Maniphest Tasks: T4659

Differential Revision: https://secure.phabricator.com/D10119

src/infrastructure/query/policy/PhabricatorCursorPagedPolicyAwareQuery.php

@@ -570,7 +570,7 @@ abstract class PhabricatorCursorPagedPolicyAwareQuery
 
       $joins[] = qsprintf(
         $conn_r,
-        'JOIN %T %T ON %T.objectPHID = %Q
+        'LEFT JOIN %T %T ON %T.objectPHID = %Q
           AND %T.indexKey = %s',
         $table,
         $alias,