Remove message about setting default port

Default port can no longer be set by changing server.js, let's just
remove this message. In future we should add something to the docs on
setting port numbers, and then we can link users to that.

Co-authored-by: Joe Lanman <joe.lanman@digital.cabinet-office.gov.uk>

lib/utils.js

@@ -92,7 +92,6 @@ exports.findAvailablePort = function (app, callback) {
           callback(port)
         } else {
           // User answers no - exit
-          console.log('\nYou can set a new default port in server.js, or by running the server with PORT=XXXX')
           console.log('\nExit by pressing \'ctrl + c\'')
           process.exit(0)
         }