Summary:
Some widget cannot be managed by KCModule, so we have to disable the widget if the property is immutable.
Remove unused parameter in `createConnections()`
Test Plan: Add [$i] right after the key or group in kwinrc, the widget should be disabled.
Reviewers: #kwin, ervin, bport, meven, zzag
Subscribers: kwin
Tags: #kwin
Differential Revision: https://phabricator.kde.org/D28484