Remove code that duplicates functionality of KCModule.
Previously the various config items were not fully ported to using
KCModule methods, and kept custom versions of isSaveNeeded and
isDefault. When called from KWinOptions::updateUnmanagedState, these
methods incorrectly reports that there are still changes to be saved.
This patch set ports all configs in window behavior to methods provided
by KCModule, solving the problem.
BUG: 477940