Remove "arcanist project" fields

Summary: Ref T7604. Remove these "arcanist project" fields from the LiskDAO classes, but leave the data intact (there are no more read/writes to this data).

Test Plan:

• Grepped for calls to these methods.
• Ran ./bin/storage adjust to check for schema issues.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: #blessed_reviewers, epriestley

Subscribers: Korvin, epriestley

Maniphest Tasks: T7604

Differential Revision: https://secure.phabricator.com/D13012