Fix work item change type and child milestone with features field

What does this MR do and why?

Backports !262293 (merged) to 19-5-stable-ee. The change is a cherry-pick of the merged commit, with no other changes.

%19.5 turned on work_item_features_field by default (!253548 (merged)). With the flag on, two work item functions read empty widget data:

• Change type doesn't warn that fields like status, dates or weight will be lost.
• New child items created from the "Child items" widget don't inherit the parent's milestone.

Both work with the flag off. The fix reads features first, so the behavior matches the flag-off behavior again.

Resolves #633875 (closed)

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