refactor: remove unnecessary padding from lib component picker (#36073)

Library component picker and Problem bank picker iframe had unnecessary
padding resulting in multiple border/shadow in the modal.

cms/static/js/views/components/add_library_content.js

@@ -22,6 +22,7 @@ function($, _, gettext, BaseModal) {
             // Translators: "title" is the name of the current component being edited.
             titleFormat: gettext('Add library content'),
             addPrimaryActionButton: false,
+            showEditorModeButtons: false,
         }),
 
         initialize: function() {

cms/static/js/views/modals/select_v2_library_content.js

@@ -17,6 +17,7 @@ function($, _, gettext, BaseModal) {
             viewSpecificClasses: 'modal-add-component-picker confirm',
             titleFormat: gettext('Add library content'),
             addPrimaryActionButton: false,
+            showEditorModeButtons: false,
         }),
 
         events: {