Issue #2212081 by dawehner: Remove views optional handler handling.

core/modules/node/config/install/views.view.content.yml

...modules/node/config/install/views.view.content_recent.yml

core/modules/views/config/schema/views.data_types.schema.yml

core/modules/views/src/Entity/View.php

core/modules/views/src/Plugin/ViewsHandlerManager.php

core/modules/views/src/Plugin/views/BrokenHandlerTrait.php

core/modules/views/src/Plugin/views/HandlerBase.php

core/modules/views/src/Tests/ModuleTest.php

..._test_config/test_views/views.view.test_view_optional.yml

core/modules/views_ui/src/Tests/HandlerTest.php