Dump KeepClearAreas from existing data structure

There is no need to regenerate the list of applicable keep-clear-areas
from first principles, because we already save the result from the last
relevant window setup and can just read it off directly for the dump.

Flag: EXEMPT bugfix
Test: atest DisplayContentTests
Bug: 424195937
Change-Id: Ic57dd247e332e85a53c22ec88984ac2d3db7c402