Role that gets permission granted not always the administrator role

In #1698746: Needs Permissions a new permission was added and an attempt was made to add an update path that would grant that permission to the administration role so that the module would still be configurable for administrator accounts other than the site maintenance account. However, that code only runs for clean installs as far as I can see. Moreover, the code made wrong assumptions about the role ID. A Drupal installation that started out with the minimal install profile may have a completely different role at ID 3.