This reverts commit e28e6484e8.
This change tried to remove nodes from all points of reference to allow
immediate destruction. However, it missed things like the children lists
cloned by transaction states of parent nodes.
Adding all that extra cleanup would not be in the spirit of a PR
claiming to simplify teardown. Let's wait for someone to come up with a
cleaner approach instead.
Fixes: https://github.com/swaywm/sway/pull/8738