Issue #2325197 by tstoeckler, sun: Remove drupal_classloader().

core/includes/bootstrap.inc

core/includes/install.core.inc

core/lib/Drupal/Core/DrupalKernel.php

core/lib/Drupal/Core/Site/Settings.php

core/modules/simpletest/src/InstallerTestBase.php

core/modules/simpletest/src/KernelTestBase.php

core/modules/simpletest/src/WebTestBase.php

...odules/system/src/Tests/DrupalKernel/DrupalKernelTest.php

...s/system/src/Tests/System/IgnoreReplicaSubscriberTest.php

core/rebuild.php

sites/default/default.settings.php