Removed unused renderStatus() from PhabricatorProjectSubprojectsController

Summary:
rPfc9db6e2a2ee929f56eb40530bb6f1fc1b75f563 introduced private function renderStatus().
All calls to this method were removed in rP29cfcc82ef7f84580e798aebeb2abcb8ffec57d7.
Thus remove this unused method.

Test Plan: Read/grep the code in PhabricatorProjectSubprojectsController.

Reviewers: O1 Blessed Committers, valerio.bozzolan

Reviewed By: O1 Blessed Committers, valerio.bozzolan

Subscribers: tobiaswiese, valerio.bozzolan, Matthew, Cigaryno

Differential Revision: https://we.phorge.it/D25717