bug #41549 [Security] Fix opcache preload with alias classes (jderusse)

This PR was merged into the 4.4 branch.

Discussion
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[Security] Fix opcache preload with alias classes

| Q             | A
| ------------- | ---
| Branch?       | 4.4
| Bug fix?      | yes
| New feature?  | no
| Deprecations? | no
| Tickets       | Fix #39961, fix #40752
| License       | MIT
| Doc PR        | -

Commits
-------

b10b695 Fix opcache preload with alias classes

src/Symfony/Component/Security/Core/Authorization/TraceableAccessDecisionManager.php

@@ -107,4 +107,6 @@ public function getDecisionLog(): array
     }
 }
 
-class_alias(TraceableAccessDecisionManager::class, DebugAccessDecisionManager::class);
+if (!class_exists(DebugAccessDecisionManager::class, false)) {
+    class_alias(TraceableAccessDecisionManager::class, DebugAccessDecisionManager::class);
+}