Administration: Define the $title global on privacy screens.

This brings more consistency with other screens and avoids a PHP warning in `get_plugin_page_hookname()`:
{{{
preg_replace(): Passing null to parameter #3 ($subject) of type array|string is deprecated
}}}

Props ipajen, jrf, SergeyBiryukov.
Fixes #57578.
Built from https://develop.svn.wordpress.org/trunk@55263


git-svn-id: http://core.svn.wordpress.org/trunk@54796 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/privacy-policy-guide.php

@@ -17,6 +17,9 @@ if ( ! class_exists( 'WP_Privacy_Policy_Content' ) ) {
 	include_once ABSPATH . 'wp-admin/includes/class-wp-privacy-policy-content.php';
 }
 
+// Used in the HTML title tag.
+$title = __( 'Privacy Policy Guide' );
+
 add_filter(
 	'admin_body_class',
 	static function( $body_class ) {