Fix \Drupal calls should be avoided in classes, use dependency injection

Previously it was PHPStan version 1.12.27, used up to and including Core 11.1. Now we are running PHPStan version 2.1.27, in Core 11.2+ and it is more strict about ignorePaths which may not exist
https://git.drupalcode.org/project/scheduler/-/jobs/5844600#L36
Need to add (?) to indicate that the path is optional and may sometimes not exist.

Nearly every call to \Drupal has been removed / replaced. The final ones are in SchedulerManager, which has 8 remaining.

2 x \Drupal::service('workbench_moderation.moderation_information')

/** @var \Drupal\workbench_moderation\ModerationInformationInterface $moderation_info */
$moderation_info = \Drupal::service('workbench_moderation.moderation_information');

line 426 and 644

2 x \Drupal::service('extension.list.module')

$optional_folder = \Drupal::service('extension.list.module')->getPath('scheduler') . '/config/optional';

line 1235, 1238

1 x \Drupal::service('config.storage')

/** @var \Drupal\Core\Config\StorageInterface $config_storage */
$config_storage = \Drupal::service('config.storage');

line 1249

2 x \Drupal::entityDefinitionUpdateManager()

$entityUpdateManager = \Drupal::entityDefinitionUpdateManager();

line 1181, 1297

1 x \Drupal::service('entity_display.repository')

/** @var \Drupal\Core\Entity\EntityDisplayRepositoryInterface $display_repository */
$display_repository = \Drupal::service('entity_display.repository');

line 1385