Increase Drydock worker time to 24 hours

Summary:
Ref T2015.  This increases the Drydock worker lease time to 24 hours.  We noticed that some leases took longer than 2 hours when leasing from AWS (the actual resource was successfully leased at around 2 hours, 19 minutes).

24 hours should be plenty enough time to actually lease anything from EC2 (or any other leases during builds).

Test Plan: Have not yet tested this.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: epriestley, Korvin

Maniphest Tasks: T2015

Differential Revision: https://secure.phabricator.com/D10544