minor #18293 [FrameworkBundle 2.7+] Removed unused variables (iltar)

This PR was merged into the 2.7 branch.

Discussion
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[FrameworkBundle 2.7+] Removed unused variables

| Q             | A
| ------------- | ---
| Branch?       | 2.7, can be merged upwards
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | ~
| License       | MIT
| Doc PR        | ~

I noticed some unused variables in the Framework Extension. I did a project inspection in phpstorm and I found nothing else. Hence I submit this PR to make it consistent again.

Commits
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9fea1ee Removed unused variables

src/Symfony/Bundle/FrameworkBundle/DependencyInjection/FrameworkExtension.php

@@ -721,9 +721,8 @@ class FrameworkExtension extends Extension
                 ->in($dirs)
             ;
 
-            $locales = array();
             foreach ($finder as $file) {
-                list($domain, $locale, $format) = explode('.', $file->getBasename(), 3);
+                list(, $locale) = explode('.', $file->getBasename(), 3);
                 if (!isset($files[$locale])) {
                     $files[$locale] = array();
                 }