Rename geo_backfill worker configuration

https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/1883

files/gitlab-config-template/gitlab.rb.template

@@ -1396,7 +1396,7 @@ external_url 'GENERATED_EXTERNAL_URL'
 ################################################################################
 #
 # gitlab_rails['geo_bulk_notify_worker_cron'] = "*/10 * * * * *"
-# gitlab_rails['geo_backfill_worker_cron'] = "*/5 * * * *"
+# gitlab_rails['geo_repository_sync_worker_cron'] = "*/5 * * * *"
 # gitlab_rails['geo_download_dispatch_worker_cron'] = "*/10 * * * *"
 # gitlab_rails['ldap_sync_worker_cron'] = "30 1 * * *"
 # gitlab_rails['ldap_group_sync_worker_cron'] = "0 * * * *"