Revert "sidebar show add_group for all layout types"

This reverts commit f5da5da.

nodes/config/ui_base.html

@@ -1200,15 +1200,14 @@
                 }
                 return false // return false to click event to prevent default
             })
+            // add the "+ group" button
+            const groupEditButton = $(`<a href="#" class="editor-button editor-button-small nr-db-sb-list-header-button" title="${c_('layout.addGroup')}"><i class="fa fa-plus"></i></a>`).appendTo(btnGroup)
+            groupEditButton.on('click', function (evt) {
+                list.editableList('addItem')
+                evt.preventDefault()
+            })
         }
 
-        // add the "+ group" button
-        const groupEditButton = $(`<a href="#" class="editor-button editor-button-small nr-db-sb-list-header-button" title="${c_('layout.addGroup')}"><i class="fa fa-plus"></i></a>`).appendTo(btnGroup)
-        groupEditButton.on('click', function (evt) {
-            list.editableList('addItem')
-            evt.preventDefault()
-        })
-
         // if this is a group & it is not an unattached group, add the "_ spacer" button
         if (item.type === 'ui-group' && !!item.page) {
             // add the "+ spacer" button