Remove a spec that was removed in CE

See bb0cba92Signed-off-by: Rémy Coutable <remy@rymai.me>

spec/models/user_spec.rb

@@ -217,22 +217,6 @@ describe User, models: true do
 
       expect(user).to be_invalid
     end
-
-    describe 'ghost users' do
-      it 'does not allow a non-blocked ghost user' do
-        user = build(:user, :ghost)
-        user.state = 'active'
-
-        expect(user).to be_invalid
-      end
-
-      it 'allows a blocked ghost user' do
-        user = build(:user, :ghost)
-        user.state = 'blocked'
-
-        expect(user).to be_valid
-      end
-    end
   end
 
   describe "non_ldap" do