Sort Order check after Content Delete unit test (U4-6642)

ContentServiceTests.SortOrder.cs

        [Test]
        public void Delete_SortOrder_Is_Correct()
        {
            // Arrange
            var contentService = ServiceContext.ContentService;
            var root = contentService.GetById(NodeDto.NodeIdSeed + 4);
            var contentType = ServiceContext.ContentTypeService.GetContentType("umbTextpage");

            var contentList = CreateChildrenOf(contentType, root, 3);
            contentService.Save(contentList);

            var contentToDelete = contentList.ElementAt(1);

            // Act
            contentService.Delete(contentToDelete, 0);

            // Assert
            Assert.That(contentService.GetById(contentList.ElementAt(0).Id).SortOrder, Is.EqualTo(0));
            Assert.That(contentService.GetById(contentList.ElementAt(2).Id).SortOrder, Is.EqualTo(1)); // FAILS, result is 2
        }