CollectionCloner::shutdown() should not block on resetting _verifyCollectionDroppedScheduler

void CollectionCloner::_cancelRemainingWork_inlock() {

    if (_arm) {

        Client::initThreadIfNotAlready();

        _killArmHandle = _arm->kill(cc().getOperationContext());

    }

    _countScheduler.shutdown();

    _listIndexesFetcher.shutdown();

    if (_establishCollectionCursorsScheduler) {

        _establishCollectionCursorsScheduler->shutdown();

    }

    if (_verifyCollectionDroppedScheduler) {

        _verifyCollectionDroppedScheduler->shutdown();

        _verifyCollectionDroppedScheduler.reset();

    }

    _dbWorkTaskRunner.cancel();

}