Shared constraint validation seems to fail in HibernateSpec unit tests on non-domain Validateable object with Grails 3.3.10

Related to issue #10782

- [x] Steps to reproduce provided
- [x] 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

1. Create a non domain object with Validateable trait
2. Create a default constraint in application.groovy
3. try and use that shared constraint from the non-domain object.

### Expected Behaviour

The shared constraint should be used

### Actual Behaviour

The shared constraint is not found, a ValidationConfigurationException is thrown with the message
Property [...] references shared constraint [...:null], which doesn't exist!
at org.grails.datastore.gorm.validation.constraints.eval.DefaultConstraintEvaluator.applySharedConstraints(DefaultConstraintEvaluator.java:201)
at org.grails.datastore.gorm.validation.constraints.eval.DefaultConstraintEvaluator.evaluate(DefaultConstraintEvaluator.java:176)
at grails.validation.Validateable$Trait$Helper.validate(Validateable.groovy:161)
at grails.validation.Validateable$Trait$Helper.validate(Validateable.groovy:93)

### Environment Information

- **Operating System**: Windows
- **Grails Version:** 3.3.10
- **JDK Version:** 1.8
- **Container Version (If Applicable):** none

### Example Application

git@github.com:tircnf/sharedValidatable.git

The example has one domain object marked with Validateable, one integration test, and two unit tests. (one which is a HibernateSpec).

The custom validator should always cause validation to fail, with the error code 'junk'.

The custom validator is applied to the integration test (ticket #10782 ), but doesn't get applied in unit tests.

The unit tests pass for Domain object, just not for non-domain objects.

Start with DefaultConstraintEvaluator.applySharedConstraints and the Validateable.groovy validate path shown in the stacktrace. Reproduce the issue with the sharedValidatable example application, comparing its HibernateSpec tests for domain and non-domain Validateable objects. Done means the shared constraint and custom validator apply in the non-domain unit test, producing the expected 'junk' error code.

Written by the indexing model from the issue text.