Merge branch '5.3' into 5.4

* 5.3:
  Fix iterrator in ServiceConfigurator
  Add Slovak lang translation #41081
  [Validator] Add missing thai translation
  [Translation] Add Burmese translation
  [Notifier] Update FirebaseTransport.php
  [FrameworkBundle] Remove translation data_collector BEFORE adding it to profiler

Author: derrabus