noded: Abstract hard-coded sys.exit value

On machines without the ssl file noded exists '5'.
Changing this to constants.EXIT_NOTCLUSTER.

Also utils.GetNodeDaemonPort hasn't risen errors.ConfigurationError for
a while, so removing that try/except block.

Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Michael Hanselmann <hansmi@google.com>