Remove ScheduleTimezoneStorage

Because it's nowhere used anymore.

Author: jrauh01

application/controllers/ScheduleController.php

@@ -12,7 +12,6 @@
 use Icinga\Module\Notifications\Forms\RotationConfigForm;
 use Icinga\Module\Notifications\Forms\ScheduleForm;
 use Icinga\Module\Notifications\Model\Schedule;
-use Icinga\Module\Notifications\Util\ScheduleTimezoneStorage;
 use Icinga\Module\Notifications\Web\Control\TimezonePicker;
 use Icinga\Module\Notifications\Widget\Detail\ScheduleDetail;
 use Icinga\Module\Notifications\Widget\RecipientSuggestions;
@@ -39,8 +38,6 @@ public function indexAction(): void
             $this->httpNotFound(t('Schedule not found'));
         }
 
-        ScheduleTimezoneStorage::setScheduleTimezone($schedule->timezone);
-
         $this->addTitleTab(sprintf(t('Schedule: %s'), $schedule->name));
 
         $this->controls->addHtml(