toddlers: mount the email_overrides file which is needed for the new packager_bugzilla_sync toddler
    
    That toddler sync packagers from FAS to bugzilla and thus
    needs to know the bugzilla email of the FAS account, which
    means it needs to know the bugzilla overrides.
    
    Signed-off-by: Pierre-Yves Chibon <pingou@pingoured.fr>