Remove "disabled" look to subprojects/workboard nav items

Summary: Fixes T12330. Minor UI nit, since we use "disabled" to usually mean "no permission". Makes these links always normal looking.

Test Plan: Review a new project in sandbox.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T12330

Differential Revision: https://secure.phabricator.com/D17436