Avoid dangling KConfigDialogManagers
A manager is created with a parent new KConfigDialogManager(QObject *parent); this parent is a parameter to the addConfig method and external to KCModule.
KCModules also explicitly deletes managers.
Typically it would have the same parent as the KCModule which is why it hasn't been a big issue so far.
Having a parent whilst being explicitly managed is an anti-pattern, but at a minimum we should clear up our list as we go so we don't risk a double delete.