Remove "project.name" from `.arcconfig"

Summary: Ref T7604. Remove the project.name configuration from .arcconfig. Depends on D12999.

Test Plan: N/A

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Maniphest Tasks: T7604

Differential Revision: https://secure.phabricator.com/D13002