Use new layout as identifier when not backend_layout is selected

[saedinia]

I created a new template in Backend Layout and everything works fine. My problem is that if no template is selected, the default template is selected. How to define the new backend Layout as default

[benjaminkott]

Please see: https://github.com/benjaminkott/bootstrap_package/blob/master/Configuration/TypoScript/setup.typoscript#L64-L90