Merge branch '5.3' into 5.4

* 5.3:
  [Security] Do not overwrite already stored tokens for REMOTE_USER authentication
  [Validator] Fix validation for single level domains
  Fix redundant type casts
  Increased the reserved memory from 10k to 32k
  [DoctrineBridge] Add DbalLoggerTest to group legacy
  Leverage DBAL's getNativeConnection() method
  Fix idempotency of LocoProvider write method

Author: nicolas-grekas

ErrorHandler.php

@@ -111,7 +111,7 @@ class ErrorHandler
     public static function register(self $handler = null, bool $replace = true): self
     {
         if (null === self::$reservedMemory) {
-            self::$reservedMemory = str_repeat('x', 10240);
+            self::$reservedMemory = str_repeat('x', 32768);
             register_shutdown_function(__CLASS__.'::handleFatalError');
         }