Upgrade/Install: Fix broken sprintf() call when deleting a backup.

In `WP_Upgrader::delete_temp_backup()`, a malformed `sprintf()` call did not pass the value, triggering a Warning in PHP 7 and a Fatal Error in PHP 8.

This fixes the malformed `sprintf()` call by correctly passing the value.

Follow-up to [55720].

Props akihiroharai, afragen.
Fixes #59320.
Built from https://develop.svn.wordpress.org/trunk@56550


git-svn-id: http://core.svn.wordpress.org/trunk@56062 1a063a9b-81f0-0310-95a4-ce76da25c4cd

wp-admin/includes/class-wp-upgrader.php

@@ -1207,8 +1207,7 @@ class WP_Upgrader {
 			if ( ! $wp_filesystem->delete( $temp_backup_dir, true ) ) {
 				$errors->add(
 					'temp_backup_delete_failed',
-					sprintf( $this->strings['temp_backup_delete_failed'] ),
-					$args['slug']
+					sprintf( $this->strings['temp_backup_delete_failed'], $args['slug'] )
 				);
 				continue;
 			}