Merge branch '6.3' into 6.4

* 6.3:
  [6.3] Remove unused test fixture
  [5.4] Remove unused test fixtures
  [Dotent] Add PHPDoc for `$overrideExistingVars`
  [SecurityBundle] Fix missing login-link element in xsd schema
  [Validator] Add missing Chinese translations #51934
  [Serializer] Fix using `DateIntervalNormalizer` with union types
  [Validator] fix: add missing translations for for Thai (th)
  fix #52273 [doctrine-messenger] DB table locks on messenger_messages with many failures
  [Serializer] Handle defaultContext for DateTimeNormalizer
  declare constructor argument as optional for backwards compatibility
  [CI] Add step to verify symfony/deprecation-contracts requirements

Dotenv.php

@@ -89,10 +89,11 @@ public function load(string $path, string ...$extraPaths): void
      * .env.local is always ignored in test env because tests should produce the same results for everyone.
      * .env.dist is loaded when it exists and .env is not found.
      *
-     * @param string      $path       A file to load
-     * @param string|null $envKey     The name of the env vars that defines the app env
-     * @param string      $defaultEnv The app env to use when none is defined
-     * @param array       $testEnvs   A list of app envs for which .env.local should be ignored
+     * @param string      $path                 A file to load
+     * @param string|null $envKey               The name of the env vars that defines the app env
+     * @param string      $defaultEnv           The app env to use when none is defined
+     * @param array       $testEnvs             A list of app envs for which .env.local should be ignored
+     * @param bool        $overrideExistingVars Whether existing environment variables set by the system should be overridden
      *
      * @throws FormatException when a file has a syntax error
      * @throws PathException   when a file does not exist or is not readable
@@ -173,7 +174,7 @@ public function overload(string $path, string ...$extraPaths): void
      * Sets values as environment variables (via putenv, $_ENV, and $_SERVER).
      *
      * @param array $values               An array of env variables
-     * @param bool  $overrideExistingVars true when existing environment variables must be overridden
+     * @param bool  $overrideExistingVars Whether existing environment variables set by the system should be overridden
      */
     public function populate(array $values, bool $overrideExistingVars = false): void
     {