minor #31631 Fixes a small doc blocks syntax error (michaelKaefer)

This PR was submitted for the master branch but it was merged into the 3.4 branch instead (closes #31631).

Discussion
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Fixes a small doc blocks syntax error

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

Commits
-------

34d4fa6 Fixes a small doc blocks syntax error

src/Symfony/Component/HttpFoundation/Request.php

@@ -2050,7 +2050,7 @@ private function setPhpDefaultLocale($locale)
         }
     }
 
-    /*
+    /**
      * Returns the prefix as encoded in the string when the string starts with
      * the given prefix, false otherwise.
      *