Hello Dennis,
you can drag&drop the "Inhalt" Tab to the left side (and click the check mark symbol on the very right) to merge the two views and then select another Tab ("Indexdaten" in your case). This will be saved in the browser localStorage per object type. So if your e2e tests use the same browser and object type it will stay that way.
Other than that there is unfortunately no configurable way to remove the preview - except for building a custom client.
Regards
Nicolai