minor #54808 [TwigBundle] Remove obsolete class_exists() call (derrabus)

This PR was merged into the 7.1 branch.

Discussion
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[TwigBundle] Remove obsolete class_exists() call

| Q             | A
| ------------- | ---
| Branch?       | 7.1
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Issues        | N/A
| License       | MIT

Given that we require Twig >= 3, I believe we don't need to trigger the autoloader at this point anymore.

Commits
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f2a13b2 [TwigBundle] Remove obsolete class_exists() check

src/Symfony/Bundle/TwigBundle/DependencyInjection/Configurator/EnvironmentConfigurator.php

@@ -15,9 +15,6 @@
 use Twig\Environment;
 use Twig\Extension\CoreExtension;
 
-// BC/FC with namespaced Twig
-class_exists(Environment::class);
-
 /**
  * Twig environment configurator.
  *