After reloading transactions for the recipient while building transaction mail, put them in the input order

Summary:
Ref T13303. In D20525 I fixed an issue where transaction rendering could use cached values with the wrong viewer by reloading transactions.

However, reloading transactions may also reorder them as a side effect, since withPHIDs(...) does not imply an order. This can make transaction rendering order in mail wrong/inconsistent.

Instead, reorder the transactions before continuing so mail transaction order is consistent.

Test Plan: Applied a group of transactions to a task, saw a more consistent rendering order in mail after the change.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13303

Differential Revision: https://secure.phabricator.com/D20563