Remove the deprecated ArcanistWorkCopyIdentity::getConfig method.

Summary: This method has been deprecated for a while now (see rARC0d212ccf5a7ac5fc75d2d3036cb3a0bee220fd02). It should be safe to remove.

Test Plan: N/A

Reviewers: epriestley, #blessed_reviewers

Reviewed By: epriestley, #blessed_reviewers

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D9466

src/workingcopyidentity/ArcanistWorkingCopyIdentity.php

@@ -252,14 +252,6 @@ final class ArcanistWorkingCopyIdentity {
     return $this->projectConfig;
   }
 
-  /**
-   * Deprecated; use @{method:getProjectConfig}.
-   */
-  public function getConfig($key, $default = null) {
-    return $this->getProjectConfig($key, $default);
-  }
-
-
   /**
    * Read a configuration directive from project configuration. This reads ONLY
    * permanent project configuration (i.e., ".arcconfig"), not other