Use 'parent' property instead of 'children' to build SF tree.

Extract the updating children/parents part out of tree builder and into child classes. They were previously all having to jump through 1+ hoops to address other traces' quirks.

Fixes: 341292609
Test: npm run test:unit:ci
Change-Id: Iec0742f5f38ffd69654627baa164466fc60a209c
5 files changed