Until now, the validation check would only get tripped up
if generic workers are used, combined with at least one EACH
other type of specialized workers.

This means that someone doing this:

```
matrix_synapse_workers_preset: one-of-each
matrix_synapse_workers_client_reader_workers_count: 5
```

.. would not have triggered this safety check.

Related to https://github.com/spantaleev/matrix-docker-ansible-deploy/pull/3100