Issue #1848058 by ACF: Added Change system test variables to the state system.

.../system/lib/Drupal/system/Tests/Module/DependencyTest.php

...stem/lib/Drupal/system/Tests/Module/EnableDisableTest.php

...s/system/lib/Drupal/system/Tests/Module/ModuleApiTest.php

...s/system/lib/Drupal/system/Tests/System/FrontPageTest.php

...modules/system/tests/modules/image_test/image_test.module

...dules/system/tests/modules/module_test/module_test.module

core/modules/system/tests/modules/path_test/path_test.module

...dules/system/tests/modules/system_test/system_test.module