minor #30829 [EventDispatcher] cleanup (ro0NL)

This PR was merged into the 3.4 branch.

Discussion
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[EventDispatcher] cleanup

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | #...   <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | symfony/symfony-docs#... <!-- required for new features -->

forgotten in #29411 (https://github.com/symfony/symfony/pull/29411/files#diff-a72bc1daccda0ec7bfcfae0e8d3df141L287)

Commits
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19134c0 [EventDispatcher] cleanup

src/Symfony/Component/EventDispatcher/Debug/TraceableEventDispatcher.php

@@ -290,10 +290,6 @@ private function postProcess($eventName)
                 if (null !== $this->logger) {
                     $this->logger->debug('Notified event "{event}" to listener "{listener}".', $context);
                 }
-
-                if (!isset($this->called[$eventName])) {
-                    $this->called[$eventName] = new \SplObjectStorage();
-                }
             } else {
                 $this->callStack->detach($listener);
             }