Use Yoast SEO meta title in site search

For more information, see Yoast SEO title and description in site search results.

$title = '';
if( is_search() && function_exists( 'wpseo_replace_vars' ) ) {
	global $post;
	$title = get_post_meta( get_the_ID(), '_yoast_wpseo_title', true );
	$title = wpseo_replace_vars( $title, $post );
}
if( empty( $title ) ) {
	$title = get_the_title();
}