Children of editor-only actors do not maintain correct transforms when placed inside level instances for PIE and cooked builds

We have found an issue where children of editor-only actors get wrong transforms in PIE and cooked builds when placed inside level instances. This affects both engine version 5.5 and 5.6. The issue occurs when the EOA's are rotated, and the level instance is offset in position from world position 0,0,0. We have found that changing

{{const FTransform TransformToApply = PackageObjectMapping->ContainerTransform * PackageObjectMapping->EditorOnlyParentTransform; }}

to

{{const FTransform TransformToApply = PackageObjectMapping->EditorOnlyParentTransform * PackageObjectMapping->ContainerTransform; }}

in Engine/Source/Runtime/Engine/Private/WorldPartition/WorldPartitionLevelHelper.cpp solves the issue.

USING PROVIDED REPRO LEVEL:

1. Open L_ReproLevel
2. Load the whole region using the World Partition Editor window
3. Observe the positions of actors inside LI_ReproLevelInstance
4. Run PIE
5. Observe how the positions of aforementioned actors change

NOT USING PROVIDED REPRO LEVEL:

1. Open a world partitioned level
2. Add an actor (A_Parent) to the level
3. Set the actor to be editor only (Cooking > Advanced > Is Editor Only Actor = true)
4. Add another actor (A_Child) to the level (use e.g. a static mesh actor with a static mesh, as it will be easiest to observe the issue if the actor is clearly visible)
5. Make A_Child a child of A_Parent
6. Rotate A_Parent 45 degrees around the Z-axis (most rotations will produce the issue, except any that correspond to a rotation of 0 in all axes)
7. Create a Level Instance (LI) from A_Parent and A_Child
8. Set LIs location to 10, 10, 0 (any location offset from world 0,0,0 will produce the issue)
9. Run PIE
10. Observe how the position of A_Child changes