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

Tests/DataCollector/HttpClientDataCollectorTest.php

@@ -9,6 +9,8 @@
  * file that was distributed with this source code.
  */
 
+namespace Symfony\Component\HttpClient\Tests\DataCollector;
+
 use PHPUnit\Framework\TestCase;
 use Symfony\Component\HttpClient\DataCollector\HttpClientDataCollector;
 use Symfony\Component\HttpClient\NativeHttpClient;
@@ -19,9 +21,13 @@
 
 class HttpClientDataCollectorTest extends TestCase
 {
-    public function testItCollectsRequestCount()
+    public static function setUpBeforeClass(): void
     {
         TestHttpServer::start();
+    }
+
+    public function testItCollectsRequestCount()
+    {
         $httpClient1 = $this->httpClientThatHasTracedRequests([
             [
                 'method' => 'GET',
@@ -50,7 +56,6 @@ public function testItCollectsRequestCount()
 
     public function testItCollectsErrorCount()
     {
-        TestHttpServer::start();
         $httpClient1 = $this->httpClientThatHasTracedRequests([
             [
                 'method' => 'GET',
@@ -80,7 +85,6 @@ public function testItCollectsErrorCount()
 
     public function testItCollectsErrorCountByClient()
     {
-        TestHttpServer::start();
         $httpClient1 = $this->httpClientThatHasTracedRequests([
             [
                 'method' => 'GET',
@@ -113,7 +117,6 @@ public function testItCollectsErrorCountByClient()
 
     public function testItCollectsTracesByClient()
     {
-        TestHttpServer::start();
         $httpClient1 = $this->httpClientThatHasTracedRequests([
             [
                 'method' => 'GET',
@@ -146,7 +149,6 @@ public function testItCollectsTracesByClient()
 
     public function testItIsEmptyAfterReset()
     {
-        TestHttpServer::start();
         $httpClient1 = $this->httpClientThatHasTracedRequests([
             [
                 'method' => 'GET',

Tests/HttplugClientTest.php

@@ -22,8 +22,6 @@
 
 class HttplugClientTest extends TestCase
 {
-    private static $server;
-
     public static function setUpBeforeClass(): void
     {
         TestHttpServer::start();

Tests/Psr18ClientTest.php

@@ -21,8 +21,6 @@
 
 class Psr18ClientTest extends TestCase
 {
-    private static $server;
-
     public static function setUpBeforeClass(): void
     {
         TestHttpServer::start();