move env flag to correct place in credhub login prompt
move env flag to correct place in credhub login prompt

Signed-off-by: Will Gant <d8a810e7448ab72c0faa0369ec09e9c977d142c5@engineerbetter.com>

EngineerBetter/concourse-up,EngineerBetter/concourse-up,EngineerBetter/concourse-up