Don't treat Quicksand requests as isWorkflow() or isAjax()

Summary:
Fixes T7061. Although it's very simple, I think this is a complete fix.

Quicksand technically is Ajax and uses Workflow as a transport mechanism, but the server should always pretend the user clicked a normal link when rendering.

Test Plan: Links that were autoconverting into dialogs (like "Edit Task") or otherwise making the wrong behavioral choices now work as expected.

Reviewers: btrahan, chad

Reviewed By: chad

Subscribers: epriestley

Maniphest Tasks: T7061

Differential Revision: https://secure.phabricator.com/D12194