Fix(testing): Register shutdown handler to delete temp input file

- Register shutdown function to delete the temporary input file via FileSystem::delete
- Avoid leftover test artifacts by removing fixture-derived files on process exit
- Return $inputFilePath and ensure it is cleaned up after tests

Author: guanguans

src/Testing/PHPUnit/AbstractRectorTestCase.php

@@ -152,6 +152,7 @@ protected function doTestFile(string $fixtureFilePath, bool $includeFixtureDirec
 
         // to remove later in tearDown()
         $this->inputFilePath = $inputFilePath;
+        register_shutdown_function([FileSystem::class, 'delete'], $inputFilePath);
 
         if ($fixtureFilePath === $inputFilePath) {
             throw new ShouldNotHappenException('Fixture file and input file cannot be the same: ' . $fixtureFilePath);