Fix --skip-themes for WordPress 6.4 (wp-cli#5840)

WordPress 6.4 added some memoization that impacts
`get_template_directory()` and `get_stylesheet_directory()`.
Fortunately, we only need to noop the global to fix `--skip-themes`.

features/requests.feature

@@ -25,6 +25,7 @@ Feature: Requests integration with both v1 and v2
 
     Given a WP installation
     And I run `vendor/bin/wp core update --version=5.8 --force`
+    And I run `rm -r wp-content/themes/*`
 
     When I run `vendor/bin/wp core version`
     Then STDOUT should contain:
@@ -46,6 +47,7 @@ Feature: Requests integration with both v1 and v2
   Scenario: Current version with WordPress-bundled Requests v1
     Given a WP installation
     And I run `wp core update --version=5.8 --force`
+    And I run `rm -r wp-content/themes/*`
 
     When I run `wp core version`
     Then STDOUT should contain:

php/WP_CLI/Runner.php

@@ -1793,6 +1793,12 @@ public function action_setup_theme_wp_cli_skip_themes() {
 			add_filter( $hook, $wp_cli_filter_active_theme, 999 );
 		}
 
+		// Noop memoization added in WP 6.4.
+		// phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound -- WordPress core global.
+		$GLOBALS['wp_stylesheet_path'] = null;
+		// phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound -- WordPress core global.
+		$GLOBALS['wp_template_path'] = null;
+
 		// Remove theme-related actions not directly tied into the theme lifecycle.
 		if ( WP_CLI::get_runner()->config['skip-themes'] ) {
 			$theme_related_actions = [
@@ -1812,6 +1818,11 @@ static function () use ( $hooks, $wp_cli_filter_active_theme ) {
 				foreach ( $hooks as $hook ) {
 					remove_filter( $hook, $wp_cli_filter_active_theme, 999 );
 				}
+				// Noop memoization added in WP 6.4 again.
+				// phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound -- WordPress core global.
+				$GLOBALS['wp_stylesheet_path'] = null;
+				// phpcs:ignore WordPress.NamingConventions.PrefixAllGlobals.NonPrefixedVariableFound -- WordPress core global.
+				$GLOBALS['wp_template_path'] = null;
 			},
 			0
 		);