Issue #1757300 by slv_ | dawehner: Remove convert_options() on argument validators.

...ugin/views/argument_default/ArgumentDefaultPluginBase.php

lib/Drupal/views/Plugin/views/argument_default/Fixed.php

lib/Drupal/views/Plugin/views/argument_default/Php.php

.../views/argument_validator/ArgumentValidatorPluginBase.php

lib/Drupal/views/Plugin/views/argument_validator/Php.php

lib/Views/node/Plugin/views/argument_validator/Node.php

lib/Views/taxonomy/Plugin/views/argument_validate/Term.php

lib/Views/user/Plugin/views/argument_default/User.php

lib/Views/user/Plugin/views/argument_validator/User.php