bug #21803 [master] Fix issues reported by static analyse (romainneutron)

This PR was merged into the 3.3-dev branch.

Discussion
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[master] Fix issues reported by static analyse

| Q             | A
| ------------- | ---
| Branch?       | master
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| License       | MIT

Follow-up #21802

Commits
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671694d [master] Fix issues reported by static analyse

Author: nicolas-grekas

DependencyInjection/Compiler/CachePoolClearerPass.php

@@ -11,6 +11,7 @@
 
 namespace Symfony\Bundle\FrameworkBundle\DependencyInjection\Compiler;
 
+use Symfony\Component\Cache\Adapter\AbstractAdapter;
 use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
 use Symfony\Component\DependencyInjection\ContainerBuilder;
 use Symfony\Component\DependencyInjection\Reference;