MC-3945: Background image of Tab only show a half inside Block Content Type

 - fix empty tab styling

Author: cspruiell

app/code/Magento/PageBuilder/view/adminhtml/web/css/source/content-type/tabs/_default.less

@@ -183,7 +183,7 @@ div[data-role='tabs'] {
         border: 1px solid @color-gray;
         border-top: none;
 
-        [data-role='tab-item'] {
+        [data-role='tab-item'] &:not(.empty-placeholder) {
             box-sizing: content-box;
             min-height: inherit;