(#18268) Service start mode in UI execute

The service start mode in the UI execute sequence should still be called as it
will allow the service to install even when the GUI install is used.
(#18268) Remove unnecessary startup mode components

This removes a property and a default value that are unnecessary to the startup
mode. This also removes three custom actions that could potentially cause
issues if they are not called in all scenarios (i.e. repair mode).