Multisite: Remove theme from network allowed themes when deleted

Previously, a deleted theme would remain in the list of allowed themes until manually cleared. This uses `WP_Theme::network_disable_theme()`, added in [37202].

Fixes #34182.


git-svn-id: https://develop.svn.wordpress.org/trunk@37203 602fd350-edb4-49c9-b593-d223f7449a82

src/wp-admin/includes/theme.php

@@ -83,6 +83,11 @@ function delete_theme($stylesheet, $redirect = '') {
 		}
 	}
 
+	// Remove the theme from allowed themes on the network.
+	if ( is_multisite() ) {
+		WP_Theme::network_disable_theme( $stylesheet );
+	}
+
 	// Force refresh of theme update information.
 	delete_site_transient( 'update_themes' );