Add explicit limits to unit test/lint error names

Summary:
Fixes T12981.

See new arc lint output: P2071

See new arc unit output: P2072

Test Plan: Ran arc unit/lint/diff and observed new error instead of a Conduit error

Reviewers: epriestley

Reviewed By: epriestley

Subscribers: Korvin

Maniphest Tasks: T12981

Differential Revision: https://secure.phabricator.com/D18603