Resolve "Aktionsmenü liegt teilweise unter dem Footer"

Closes #2389

Merge request studip/studip!1598

resources/assets/stylesheets/scss/layouts.scss

@@ -229,7 +229,6 @@ body {
     grid-row: 3 / 4;
     justify-content: space-between;
     line-height: $footer-height - 4px;
-    z-index: 1000;
 }
 
 #main-footer-info {