Give all commands from DiffusionCommandEngine a default 15 minute timeout
Summary:
Ref T13108. See PHI364. See the task and issue for discussion.
If a git fetch during synchronization hangs, the whole node currently hangs. While the causes of a git fetch hang aren't clear, we don't expect synchronization to ever reasonably take more than 15 minutes, so add a default timeout.
Test Plan: Will deploy and observe; this is difficult to reproduce or test directly.
Maniphest Tasks: T13108
Differential Revision: https://secure.phabricator.com/D19235