Remove an example that is no longer necessary

spec/models/group_spec.rb

@@ -994,13 +994,4 @@ describe Group do
       expect(group.project_creation_level).to eq(Gitlab::CurrentSettings.default_project_creation)
     end
   end
-
-  describe 'subgroup_creation_level' do
-    it 'outputs the default one if it is nil' do
-      group = create(:group, subgroup_creation_level: nil)
-
-      expect(group.subgroup_creation_level)
-        .to eq(::Gitlab::Access::MAINTAINER_SUBGROUP_ACCESS)
-    end
-  end
 end