Issue #2315807 by tim.plunkett: Remove support for path-based form redirects.

core/includes/batch.inc

core/includes/form.inc

core/lib/Drupal/Core/Annotation/Action.php

core/lib/Drupal/Core/Form/FormState.php

core/lib/Drupal/Core/Form/FormStateInterface.php

core/lib/Drupal/Core/Form/FormSubmitter.php

core/lib/Drupal/Core/Form/FormSubmitterInterface.php

...les/content_translation/src/ContentTranslationHandler.php

core/modules/field_ui/src/FieldOverview.php

core/modules/field_ui/src/FieldUI.php

core/modules/field_ui/src/Form/FieldInstanceEditForm.php

core/modules/field_ui/src/Form/FieldStorageEditForm.php

core/modules/file/file.module

core/modules/node/src/Plugin/Action/DeleteNode.php

core/modules/path/src/Form/DeleteForm.php

core/modules/system/src/Plugin/views/field/BulkForm.php

core/modules/system/system.module

...m/tests/modules/ajax_test/src/Form/AjaxTestDialogForm.php

...modules/form_test/src/Form/FormTestCheckboxesZeroForm.php

...tests/modules/form_test/src/Form/FormTestRedirectForm.php