[1.9.x] Refs #22634 -- Removed unneeded app_label in custom session engine example.

    class CustomSession(AbstractBaseSession):

        account_id = models.IntegerField(null=True, db_index=True)

        class Meta:

            app_label = 'mysessions'

        @classmethod

        def get_session_store_class(cls):

            return SessionStore