Island: Remove unlock() and reset_key() from RepositoryService

These two methods violate SRP and ISP.

monkey/monkey_island/cc/services/repository_service.py

@@ -34,12 +34,6 @@ class RepositoryService:
         if custom_pbas.windows_filename:
             self._file_repository.delete_file(custom_pbas.windows_filename)
 
-    def unlock(self):
-        raise NotImplementedError
-
-    def reset_key(self):
-        raise NotImplementedError
-
     def clear_simulation_data(self):
         # NOTE: This method will be replaced by an event when we implement pub/sub in the island.
         #       Different plugins and components will be able to register for the event and clear