implicitly add (clusto_type=server) filter when running ssh-list/root-ssh-list/etc, unless there's already an equality or inequality condition involving clusto_type

Summary: Fixes T19507

Reviewers: dchen, xiaojian, bigo, nharkins

Reviewed By: nharkins

Maniphest Tasks: T19507

Differential Revision: https://code.uberinternal.com/D45163