Remove "Recent Commits" from repository landing page

Summary:
Ref T13552. Currently, the repository landing page has a panel with recent commits. This is accessible by clicking "History" and usually below the fold, so it's not clearly useful.

Since I'm consolidating this code anyway to fix an issue with the import pipeline, just get rid of this history view.

Test Plan: Viewed a repository landing page, no longer saw a history panel.

Maniphest Tasks: T13552

Differential Revision: https://secure.phabricator.com/D21408