Issue #3079788 by Spokje, mondrake: Remove phpunit4 polyfills from 8.8.x

...ts/Component/Bridge/ZfExtensionManagerSfContainerTest.php

...ests/Drupal/Tests/Component/Datetime/DateTimePlusTest.php

...pal/Tests/Component/DependencyInjection/ContainerTest.php

...ependencyInjection/Dumper/OptimizedPhpArrayDumperTest.php

.../Tests/Component/Discovery/YamlDirectoryDiscoveryTest.php

...Drupal/Tests/Component/FileCache/FileCacheFactoryTest.php

...sts/Drupal/Tests/Component/Gettext/PoStreamWriterTest.php

...sts/Drupal/Tests/Component/Plugin/Context/ContextTest.php

...ests/Drupal/Tests/Component/Plugin/DefaultFactoryTest.php

...l/Tests/Component/Plugin/Discovery/DiscoveryTraitTest.php

...mponent/Plugin/Discovery/StaticDiscoveryDecoratorTest.php

.../Tests/Component/Plugin/Factory/ReflectionFactoryTest.php

...s/Drupal/Tests/Component/Plugin/PluginManagerBaseTest.php

...sts/Drupal/Tests/Component/Serialization/YamlPeclTest.php

.../Drupal/Tests/Component/Serialization/YamlSymfonyTest.php

core/tests/Drupal/Tests/Component/Serialization/YamlTest.php

.../Drupal/Tests/Component/Utility/ArgumentsResolverTest.php

core/tests/Drupal/Tests/Component/Utility/ColorTest.php

core/tests/Drupal/Tests/Component/Utility/CryptTest.php

...sts/Drupal/Tests/Component/Utility/EmailValidatorTest.php