R1:2c43d055b191

Remove old ObjectBox tab cruft

Summary: Ref T10628. Cleans up remaining weird, unused tab behaviors in ObjectBoxView to simplify ObjectBox.

Test Plan: Toggled tabs in Files.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T10628

Differential Revision: https://secure.phabricator.com/D16208