Spring wiring in DataStore services is not working correctly

Don't know if this belongs in this repo or grails-core.

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issue.

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### Task List

- [x] Steps to reproduce provided
- [ ] Stacktrace (if present) provided
- [x] Example that reproduces the problem uploaded to Github
- [x] Full description of the issue provided (see below)

### Steps to Reproduce

If you initialise/create any services as interfaces or abstract classes and use the `grails.gorm.services.Service` annotation, and then also wire in the grailsApplication to verify, none of the annotated classes are included inside the Service artefact type. Even if they are in the `grails-app/services` folder, and end in `Service`.
I believe this is affecting wiring of spring bean dependencies.

### Expected Behaviour

Services should be in the Service artefact list and all beans should be wired.

### Actual Behaviour

They aren't

### Environment Information

- **Operating System**: Mac OS X Sierra
- **GORM Version:** 6.1.8
- **Grails Version (if using Grails):** 3.3.1
- **JDK Version:** 8u141

### Example Application

https://github.com/olliefreeman/grails-issues

Run the `rest.api.app.NonDomainServiceSpec` integration test

Run the `rest.api.app.NonDomainServiceSpec` integration test in the linked `grails-issues` example first. Trace how `grailsApplication` discovers `grails.gorm.services.Service` classes, especially interfaces and abstract classes, and verify that the expected Service artefact entries and Spring bean wiring are present.

Written by the indexing model from the issue text.