Method "getChildren" sort ordering

[EliasKotlyar]

Issue is described here:
magento/magento2#11310

This issue happens in all Magento Versions.

Steps to reproduce
Create a Code which will call the following Class:
M1: Mage_Catalog_Model_Resource_Category_Flat
M2: Magento\Catalog\Model\ResourceModel\Category\Flat

With the following Method:
getChildren()

Expected result
You will get a list of Ids of the children categories.
This list is sorted by the "position" attribute.

Actual result
You will get a list of Ids of the Children Categories.
This list is sorted by entity-id attribute.

I dont see any special case where you would need the sorting by the entity_id. More usual you will need them sorted in the same order as in the Backend(by the position attribute).