Ensure we allow author information to be sent without a card number

Shows what I know. This already works 100% as expected. The participant information is sent as long as there is a first and last name - the participant's card number is optional.

We already have test coverage that the widget does not required a card number - see:

    $this->drupalGet('node/1/edit');
    $this->assertSession()->fieldExists('field_vg_test[0][card_number]')->setValue('');
    $this->assertSession()->fieldExists('field_vg_test[0][surname]')->setValue('Smith');
    $this->assertSession()->buttonExists('Save')->press();
    $this->assertSession()->pageTextContainsOnce('article Test node for VGWort has been updated.');

in \Drupal\Tests\vgwort\FunctionalJavascript\VGWortFieldTest::testFields()

I'm adding explicit test coverage that we can generate a new message without card number details.