Editor: Do not translate the title of "Custom Styles" specific posts.

This change removes the internationalization of the "Custom Styles" specific posts as the post title being hardcoded is consistent with `wp_template_part` and `wp_template` post types, and is not publicly visible, except in the database. Moreover, using consistent "Custom Styles" post title may make is easier to retrieve the related posts in the database.

Props antonvlasenko, audrasjb, desrosj, hellofromTonya.
Fixes #54518.

Built from https://develop.svn.wordpress.org/trunk@52280


git-svn-id: http://core.svn.wordpress.org/trunk@51872 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-includes/class-wp-theme-json-resolver.php

@@ -273,7 +273,7 @@ class WP_Theme_JSON_Resolver {
 				array(
 					'post_content' => '{"version": ' . WP_Theme_JSON::LATEST_SCHEMA . ', "isGlobalStylesUserThemeJSON": true }',
 					'post_status'  => 'publish',
-					'post_title'   => __( 'Custom Styles', 'default' ),
+					'post_title'   => 'Custom Styles',
 					'post_type'    => $post_type_filter,
 					'post_name'    => 'wp-global-styles-' . urlencode( wp_get_theme()->get_stylesheet() ),
 					'tax_input'    => array(