Fix spacing on column moving dialogs

Summary: Specify list style: none by default. Fixes T6926

Test Plan: Look at column reorder dialog, seems spiffy again.

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T6926

Differential Revision: https://secure.phabricator.com/D11381