Issue #3399155 Remove use of file_to_return

Closes #3399155

automatic_updates_extensions/tests/src/Build/ModuleUpdateTest.php

@@ -81,11 +81,8 @@ END;
     $this->assertStringContainsString('The project new_module is not a Drupal project known to Composer and cannot be updated.', $page_text);
     $this->assertStringContainsString('new_module', $page_text);
     // Use the API endpoint to create a stage and update the 'alpha' module to
-    // 1.1.0. We ask the API to return the contents of the module's
-    // composer.json file, so we can assert that they were updated to the
-    // version we expect.
-    // @see \Drupal\automatic_updates_extensions_test_api\ApiController::run()
-    $this->getPackageManagerTestApiResponse(
+    // 1.1.0.
+    $this->makePackageManagerTestApiRequest(
       '/automatic-updates-extensions-test-api',
       [
         'projects' => [
@@ -95,6 +92,7 @@ END;
     );
 
     $updated_composer_json = $this->getWebRoot() . 'modules/contrib/alpha/composer.json';
+    // Assert the module was updated.
     $this->assertFileEquals(
       __DIR__ . '/../../../../package_manager/tests/fixtures/build_test_projects/alpha/1.1.0/composer.json',
       $updated_composer_json,