Overriding FinishedText does not show at the finish page.

This can be reproduced using this example:
https://github.com/qtproject/installer-framework/blob/11046d6f77ed2d59b7b1cdbae52f487304ce4f42/examples/systeminfo/packages/root/meta/installscript.qs#L90

put the line validOs = false to make sure CancelInstaller gets called, then build the installer and run it.

Observe the cancelled text does not show on that page.