Remove calls to drupal_get_user_timezone() in recurring_events_registration submodule

modules/recurring_events_registration/src/RegistrantListBuilder.php

@@ -113,7 +113,7 @@ class RegistrantListBuilder extends EntityListBuilder {
 
     $row['id'] = $entity->id();
     $row['series'] = $series->toLink($series->title->value);
-    $timezone = new \DateTimeZone(drupal_get_user_timezone());
+    $timezone = new \DateTimeZone(date_default_timezone_get());
     $date = $instance->date->start_date;
     $date->setTimezone($timezone);
     $row['instance'] = $instance->toLink($date->format($this->config->get('recurring_events_registration.registrant.config')->get('date_format')));

modules/recurring_events_registration/src/RegistrationCreationService.php

@@ -431,7 +431,7 @@ class RegistrationCreationService {
       $reg_type = $this->getRegistrationType();
       $reg_dates_type = $this->getRegistrationDatesType();
 
-      $timezone = new \DateTimeZone(drupal_get_user_timezone());
+      $timezone = new \DateTimeZone(date_default_timezone_get());
       $utc_timezone = new \DateTimeZone(DateTimeItemInterface::STORAGE_TIMEZONE);
 
       $now = new DrupalDateTime();