Fake site should always be used for functional tests

Closes #3394705

tests/src/Functional/AutomaticUpdatesFunctionalTestBase.php

@@ -13,7 +13,6 @@ use Drupal\Tests\BrowserTestBase;
 use Drupal\Tests\package_manager\Traits\AssertPreconditionsTrait;
 use Drupal\Tests\package_manager\Traits\ComposerStagerTestTrait;
 use Drupal\Tests\package_manager\Traits\FixtureManipulatorTrait;
-use Drupal\Tests\package_manager\Traits\FixtureUtilityTrait;
 
 /**
  * Base class for functional tests of the Automatic Updates module.
@@ -25,7 +24,6 @@ abstract class AutomaticUpdatesFunctionalTestBase extends BrowserTestBase {
   use AssertPreconditionsTrait;
   use ComposerStagerTestTrait;
   use FixtureManipulatorTrait;
-  use FixtureUtilityTrait;
   use TestSetUpTrait;
 
   /**