BUG: Incorrect nesting of adult human in the development stage filter

[MillenniumFalconMechanic]

Describe the bug

In the development stage filter, Adult (15+ years) should be a child of Postnatal human and not a sibling. See correct hierarchy in OLS. Originally reported by @jahilton in Slack.

To Reproduce

Steps to reproduce the behavior:

1. Go to Collections.
2. Click on Pediatric (0-15 years) in the development stage filter.
3. Collections with Pediatric (0-15 years) and Adult (15+ years) development stages are included in the filtered result set.

Expected behavior

Only collections with Pediatric (0-15 years) are included in the filtered result set.

Root Cause

• The backend tags each collection with their ancestors; a collection with Adult (15+ years) will have an ancestor of Postnatal human.
• The frontend development stage filter configuration defines Pediatric (0-15 years) as the only child of Postnatal human. When Pediatric (0-15 years) is selected, the frontend "rolls up" the selected value to Postnatal human. This means the collections tagged with the Postnatal human ancestor are included in the filtered result set.

Fix

Update development stage config: the adult definition needs to be moved into postnatal's children array (as the second element).