Remove various unused beahviors from PHUIWorkboardView

Summary: Ref T5240. We don't currently use any of these options and I don't think we have any plans to use them. Strip them out for now to make fixing drag-and-drop stuff easier.

Test Plan: Grepped for removed stuff, no hits.

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T5240

Differential Revision: https://secure.phabricator.com/D14864