Remove assumption about front page title from NodeCreationTest

Issue #1811622 by tim.plunkett, xjm: Remove assumption about front page title from NodeCreationTest.

Part of #1811016: [meta] Decouple tests from Node module.

NodeCreationTest currently assumes the title of the node front page is "Welcome to Drupal," and uses this to test whether the user is redirected away from the node page when an unpublished node is created. It also does not actually confirm that that the node is created.

Attached is based on @tim.plunkett's change in the VDC sandbox. Tim had removed the configuration that sets node as the front page and just changed the title assertion as in the attached. However, if we really do want to codify that the user is directed to the front page, and not just away from the node page, we should check the URL. Unfortunately, because of the way user_page() works, we can't just assertUrl('') when user is the front page, because it redirects to user/N and so fails any generic assertion I was able to come up with. So, I've left node as the front page here.