Summary: database migration + drop old view code. Fixes T5604.
Test Plan: grepped src/ for TYPE_CCS (no hits); viewed some tasks with old cc transactions and noted they still rendered correctly post data conversion
Reviewers: epriestley
Reviewed By: epriestley
Subscribers: Korvin, epriestley
Maniphest Tasks: T5604
Differential Revision: https://secure.phabricator.com/D11015
