Fix test to check Idle instead of relying on client id.
Fix test to check Idle instead of relying on client id.

Since client connections are handled in go routines, we don't have a guarantee that the second client's id will be > than the first.

apcera/gnatsd,wallyqs/gnatsd,nats-io/gnatsd,glycerine/hnatsd,ericpromislow/gnatsd,glycerine/hnatsd,wallyqs/gnatsd,nats-io/gnatsd,ericpromislow/gnatsd,glycerine/gnatsd,brkt/gnatsd,mitghi/gnatsd,glycerine/hnatsd,apcera/gnatsd,brkt/gnatsd,glycerine/gnatsd,mitghi/gnatsd