bug #25978 Deterministic proxy names (lstrojny)

This PR was merged into the 3.4 branch.

Discussion
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Deterministic proxy names

Proxy class names should be deterministic and independent of spl_object_hash() which is somewhat random to better support reproducible builds. See #25958

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

Commits
-------

b173b81 Proxy class names should be deterministic and independent of spl_object_hash() which is somewhat random

src/Symfony/Bridge/ProxyManager/LazyProxy/PhpDumper/ProxyDumper.php

@@ -108,7 +108,7 @@ public function getProxyCode(Definition $definition)
      */
     private function getProxyClassName(Definition $definition)
     {
-        return preg_replace('/^.*\\\\/', '', $definition->getClass()).'_'.substr(hash('sha256', spl_object_hash($definition).$this->salt), -7);
+        return preg_replace('/^.*\\\\/', '', $definition->getClass()).'_'.substr(hash('sha256', $definition->getClass().$this->salt), -7);
     }
 
     /**