don't start two greeters at startup

commit c0188a70 added some complex code for starting the login screen when the user switches to the initial VT if nothing is running on that VT.

The problem is, we get a VT change event on that VT as part of the start up process.

This leads to an additional greeter getting started.

This merge request adds a check to side step the new code during startup and some code to try to avoid jumping VTs to the same VT.