Remove verbose output from arc lint --trace

Summary: I think that this output was used during the early stage of ArcanistConfigurationDrivenLintEngine, but I question it's value nowadays. In particular, I find that this output makes the output of arc lint --trace significantly less useful.

Test Plan: Ran ./bin/arc lint --trace and saw useful output.

Reviewers: epriestley, Blessed Reviewers

Reviewed By: epriestley, Blessed Reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D13593