Merge branch '4.4' into 5.0

* 4.4:
  Fix abstract method name in PHP doc block
  Various cleanups
  [HttpClient] fix issues in tests
  Fixes sprintf(): Too few arguments in form transformer
  [Console] Fix QuestionHelper::disableStty()
  [Validator] Use Mime component to determine mime type for file validator
  validate subforms in all validation groups
  Update Hungarian translations
  Add meaningful message when Process is not installed (ProcessHelper)
  [PropertyAccess] Fix TypeError parsing again.
  [TwigBridge] fix fallback html-to-txt body converter
  [Form] add missing Czech validators translation
  [Validator] add missing Czech translations
  never directly validate Existence (Required/Optional) constraints

Author: nicolas-grekas

EnvVarProcessor.php

@@ -227,7 +227,7 @@ public function getEnv(string $prefix, string $name, \Closure $getEnv)
             $env = json_decode($env, true);
 
             if (JSON_ERROR_NONE !== json_last_error()) {
-                throw new RuntimeException(sprintf('Invalid JSON in env var "%s": '.json_last_error_msg(), $name));
+                throw new RuntimeException(sprintf('Invalid JSON in env var "%s": ', $name).json_last_error_msg());
             }
 
             if (null !== $env && !\is_array($env)) {