Ignore repository versions on inactive devices in "Repository Servers" panel in Config

Summary:
Fixes T11590. Currently, we incorrectly consider cluster repository versions that are (or were) on devices which are no longer part of the active cluster service when building this status screen.

Instead, ignore them. This is just a display bug; the actual ClusterEngine already had similar logic.

Test Plan:

• Added a bad leader record to repository_workingcopyversion.
• Before patch, got a bad "Partial (1w)" sync:

• After patch, got a good "Sycnchronized":

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T11590

Differential Revision: https://secure.phabricator.com/D16492