pub(crate) fn tx_rejected(
        mut self,
        description: &'static str,
        tx: Transaction,
        err: UnexecutableReason,
    ) -> Self {
        self.actions
            .push_back(ScenarioItem::Reject(description, tx, err));
        self
    }
Expect the state keeper to reject the transaction.
`err` argument is an optional substring of the expected error message. If `None` is provided, any rejection
would work. If `Some` is provided, rejection reason would be checked against the provided substring.
core/node/state_keeper/src/testonly/test_batch_executor.rs