Remove ORDER_PATH_MODIFIED from Differential

Summary:
Ref T7803. This is a performance hack, not a real order, and isn't really meaningful or pageable.

After D12158, we constraint his query on `dateModified` anyway, which should generally give the database a relatively small result set to examine.

Test Plan: Browsed Differential and Diffusion. Checked query plan, it didn't look too crazy.

Reviewers: btrahan

Reviewed By: btrahan

Subscribers: epriestley

Maniphest Tasks: T7803

Differential Revision: https://secure.phabricator.com/D12361

src/applications/differential/controller/DifferentialRevisionViewController.php

@@ -786,7 +786,7 @@ final class DifferentialRevisionViewController extends DifferentialController {
       ->setViewer($this->getRequest()->getUser())
       ->withStatus(DifferentialRevisionQuery::STATUS_OPEN)
       ->withUpdatedEpochBetween($recent, null)
-      ->setOrder(DifferentialRevisionQuery::ORDER_PATH_MODIFIED)
+      ->setOrder(DifferentialRevisionQuery::ORDER_MODIFIED)
       ->setLimit(10)
       ->needFlags(true)
       ->needDrafts(true)