Subqueues for taxonomy smartqueue not created upon config import

Problem/Motivation

When deploying a configuration with a smartqueue for a taxonomy vocabulary, none of the subqueues for the taxonomy terms are created.

I have to manually edit and save the smartqueue in order to create the subqueues.

Steps to reproduce

Starting without the module installed...

* Add some terms to any taxonomy vocabulary
* Make a database backup
* Install entityqueue and entityqueue_smartqueue
* Add a new entityqueue smartqueue for your vocabulary
* Observe that a subqueue for each term has also been created
* Export config for all changes
* Restore the database from the backup, clear caches, etc.
* Import config

The result is that the smartqueue exists at /admin/structure/entityqueue but displays "0 subqueues".

The subqueues for the pre-existing terms are only created after manually editing and saving the smartqueue config.

Proposed resolution

Unknown. I saw #2782535: Subqueue missing after config import which was resolved, but that was about "Simple" queues, so maybe there's a separate-but-similar issue with taxonomy smartqueues?

Remaining tasks

User interface changes

API changes

Data model changes