Remove -t -t from Drydock SSH interface

Summary: These arguments prevent stderr from being routed correctly for Linux hosts and break Windows entirely. Removing them fixes the issue.

Test Plan: Removed those options and both Linux and Windows hosts had their output fed back into Harbormaster correctly.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley

CC: Korvin, epriestley, aran

Maniphest Tasks: T4111, T1029

Differential Revision: https://secure.phabricator.com/D7710