Fix event dispatcher BC

[MPParsley]

The arguments to the event dispatcher are backwards compared to expected (some BC code in Symfony is allowing it for now):

$this->eventDispatcher->dispatch(GroupCreationEventInterface::EVENT_NAME, $event);

3:55
that’s in several places (the reversed arguments) (edited)

[pfrenssen]

Seems we have a lot of deprecated calls :)

  2196x: Calling the Symfony\Component\EventDispatcher\EventDispatcherInterface::dispatch() method with a string event name as the first argument is deprecated in drupal:9.1.0, an Event object will be required instead in drupal:10.0.0. See https://www.drupal.org/node/3154407