minor #57868 Remove useless code (alexandre-daubois)

This PR was merged into the 7.2 branch.

Discussion
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Remove useless code

| Q             | A
| ------------- | ---
| Branch?       | 7.2
| Bug fix?      | no
| New feature?  | no
| Deprecations? | no
| Issues        | -
| License       | MIT

I went through the remaining components and bundles, following my last PRs of this kind.

Commits
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58941cec67 Remove useless code

Author: nicolas-grekas

Store/PostgreSqlStore.php

@@ -169,7 +169,7 @@ public function exists(Key $key): bool
         $stmt = $this->getConnection()->prepare($sql);
 
         $stmt->bindValue(':key', $this->getHashedKey($key));
-        $result = $stmt->execute();
+        $stmt->execute();
 
         if ($stmt->fetchColumn() > 0) {
             // connection is locked, check for lock in internal store