worker: start WatchPermissionsUserMapping at startup

Created by: keegancsmith

Globals depends on initialization which we haven't done in worker. This lead us to always using the default value in worker. As such we always used the default value for PermissionsUserMapping inside of worker, which is email. So using username would fail. Now it works.

Test Plan: Ran setRepositoryPermissionsForBitbucketProject manually against the devserver with bindid set to username. Before this change this call would not result in repositories becoming visible for the user. After the change the repositories are visible.