Fix todos in admin view functional test

[alansaun92]

I noticed a couple of todos mentioned in the functional test AdminViewTest.

So I have moved the creation of the admin user into the setup function and added in a kernel test to confirm that the admin url that we are expecting is the one set on the manage alert banners view.

[andybroomfield]

@ekes, though the new admin view url is a kernel test so should be quicker (the AdminViewTest is a functional test). If we wanted to keep it there we could add the code to the method?

[ekes]

@ekes, though the new admin view url is a kernel test so should be quicker (the AdminViewTest is a functional test). If we wanted to keep it there we could add the code to the method?

I'd overlooked it was a Kernel test.

All good.