Remove be_not_found_for matcher

It was only used in one test, and the test was kind of redundant.

spec/features/security/profile_access_spec.rb

@@ -6,11 +6,6 @@ describe "Profile access", feature: true  do
   before do
     @u1 = create(:user)
   end
-
-  describe "GET /login" do
-    it { expect(new_user_session_path).not_to be_not_found_for :visitor }
-  end
-
   describe "GET /profile/keys" do
     subject { profile_keys_path }