Remove arguments from unit test engines

Summary: Ref T9131. This doesn't seem to be used... it seems like it is a relic of postponed test results.

Test Plan: N/A

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley, Blessed Reviewers

Subscribers: Korvin

Maniphest Tasks: T9131

Differential Revision: https://secure.phabricator.com/D14487