…ass usage to describe callables (ogizanagi)

This PR was merged into the 3.4 branch.

Discussion
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[Fwb][EventDispatcher][HttpKernel] Fix getClosureScopeClass usage to describe callables

| Q             | A
| ------------- | ---
| Branch?       | 3.4 <!-- see below -->
| Bug fix?      | yes
| New feature?  | no <!-- don't forget to update src/**/CHANGELOG.md files -->
| BC breaks?    | no     <!-- see https://symfony.com/bc -->
| Deprecations? | no <!-- don't forget to update UPGRADE-*.md and src/**/CHANGELOG.md files -->
| Tests pass?   | yes    <!-- please add some, will be required by reviewers -->
| Fixed tickets | #29054   <!-- #-prefixed issue number(s), if any -->
| License       | MIT
| Doc PR        | N/A

`\ReflectionFunctionAbstract::getClosureScopeClass` returns a `\ReflectionClass` instance, not the class name.

Before this patch:

```diff
--- Expected
+++ Actual
@@ @@
-'Symfony\Component\EventDispatcher\Tests\Debug\FooListener::listen'
+'Class [ <user> class Symfony\Component\EventDispatcher\Tests\Debug\FooListener ] {
+  @@ [...]/src/Symfony/Component/EventDispatcher/Tests/Debug/WrappedListenerTest.php 28-33
+
+  - Constants [0] {
+  }
+
+  - Static properties [0] {
+  }
+
+  - Static methods [0] {
+  }
+
+  - Properties [0] {
+  }
+
+  - Methods [1] {
+    Method [ <user> public method listen ] {
+      @@ [...]/src/Symfony/Component/EventDispatcher/Tests/Debug/WrappedListenerTest.php 30 - 32
+    }
+  }
+}
+::listen'
```

Commits
-------

61e4592 [Fwb][EventDispatcher][HttpKernel] Fix getClosureScopeClass usage to describe callables