Merge branch '6.4' into 7.1

* 6.4:
  [DoctrineBridge] Fix Connection::createSchemaManager() for Doctrine DBAL v2
  [HttpClient] Various cleanups after recent changes
  do not add child nodes to EmptyNode instances
  consider write property visibility to decide whether a property is writable
  add comment explaining why HttpClient tests are run separately
  silence warnings issued by Redis Sentinel on connection issues

Author: nicolas-grekas

SchemaListener/AbstractSchemaListener.php

@@ -24,8 +24,7 @@ abstract public function postGenerateSchema(GenerateSchemaEventArgs $event): voi
     protected function getIsSameDatabaseChecker(Connection $connection): \Closure
     {
         return static function (\Closure $exec) use ($connection): bool {
-            $schemaManager = $connection->createSchemaManager();
-
+            $schemaManager = method_exists($connection, 'createSchemaManager') ? $connection->createSchemaManager() : $connection->getSchemaManager();
             $checkTable = 'schema_subscriber_check_'.bin2hex(random_bytes(7));
             $table = new Table($checkTable);
             $table->addColumn('id', Types::INTEGER)