some reordering and test optimizations to align new API.

tests/Integration/ContainerTestCase.php

@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Testcontainers\Tests\Integration;
+
+use PHPUnit\Framework\TestCase;
+use Testcontainers\Container\GenericContainer;
+
+abstract class ContainerTestCase extends TestCase
+{
+    protected static GenericContainer $container;
+
+    protected function tearDown(): void
+    {
+        self::$container->remove();
+    }
+}