Fix old icon css

Summary:
Updated some old css to point at the new icon set
Fixes T5357

Test Plan: View it

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley, Blessed Reviewers

Subscribers: epriestley, Korvin

Maniphest Tasks: T5357

Differential Revision: https://secure.phabricator.com/D9578