Remove unused drag and drop Conpherence code

Summary: Ref T11730. Removes unused code since this is now it's own page.

Test Plan: rebuild maps, grep for javelin code, classnames

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T11730

Differential Revision: https://secure.phabricator.com/D16700