Remove obsolete setup check call to Maniphest "Can Edit <X>" field checks

Summary: Ref T13164. Missed this in D19581.

Test Plan:

• Forced setup checks to re-run by visiting Config → Setup Issues explicitly.
• Before patch: fatal on call to nonexistent method.
• After patch: setup issues.

Reviewers: amckinley

Reviewed By: amckinley

Maniphest Tasks: T13164

Differential Revision: https://secure.phabricator.com/D19593