Remove remaining arcanist project code

Summary: Fixes T7604. This is the big scary change which drops the "arcanist project" fields from the database permanently.

Test Plan:
`grep`ped for the following to ensure that I had found all remaining references:

  - `/arcanistProject/i`
  - `/arcanist_project/i`
  - `/projectName/i`
  - `/project_name/i`
  - `/project_id/i`

WARNING: Wait at least one month before landing this.

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: Korvin, epriestley

Maniphest Tasks: T7604

Differential Revision: https://secure.phabricator.com/D12899

resources/sql/autopatches/20150708.arcanistproject.sql

@@ -0,0 +1,10 @@
+ALTER TABLE {$NAMESPACE}_differential.differential_diff
+  DROP COLUMN arcanistProjectPHID;
+
+ALTER TABLE {$NAMESPACE}_differential.differential_revision
+  DROP COLUMN arcanistProjectPHID;
+
+ALTER TABLE {$NAMESPACE}_releeph.releeph_project
+  DROP COLUMN arcanistProjectID;
+
+DROP TABLE {$NAMESPACE}_repository.repository_arcanistproject;