_scheduler_content_moderation_integration_states_values should leverage content_moderation.state_transition_validation

I believe this uncovered bugs in the tests.

  public function testValidPublishStateToUnPublishStateTransition() {
    $node = Node::create([
      'type' => 'example',
      'title' => 'Test title',
      'moderation_state' => 'draft',
      'unpublish_on' => strtotime('+3 days'),
      'publish_on' => strtotime('+2 days'),
      'unpublish_state' => 'archived',
      'publish_state' => 'published',
    ]);

    $violations = $node->validate();
    $this->assertCount(0, $violations, 'Both transitions should pass validation');
  }

This is failing. But draft -> archive was never a valid transition. From draft only create_new_draft and publish are valid.

Thanks for this, @mglaman.
Moving to the 3.x branch as it would have to be done there first. Open a new MR, as we can use MR48 if it gets back-ported to 2.x