Builder: Filter out default extensions, only use extensions provided by child theme

builder_extensions_filter.php

<?php

// Filter out Builder extensions except those provided by the custom child theme
add_filter( 'builder_get_extension_directories', 'intw_set_extensions_directory' );
function intw_set_extensions_directory( $directories ) {
  $directories = array(
    get_template_directory() . '/extensions',
    get_stylesheet_directory() . '/extensions',
  );
  $directories = array_unique( $directories );
  return $directories;
}