Grails integration tests failing due to i18n message fetched during Bootstrap

I added a service method call to Boostrap.groovy in my Grails 4.0.1 application:

@GrailsCompileStatic
class BootStrap {

    GrailsApplication grailsApplication
    SelfAssessmentRatingService selfAssessmentRatingService

    def init = { servletContext ->
        TimeZone.setDefault(TimeZone.getTimeZone("UTC"))

        ...

        SelfAssessmentRating rating = SelfAssessmentRating.first()
        if (!rating) {
            selfAssessmentRatingService.createRatingsFromConfig()
        }
    }

    def destroy = {
    }
}

In the service method, an i18n message is fetched for each object I have specified in setup.selfAssessmentRatings in the application config.

@GrailsCompileStatic
@Slf4j
@Transactional
class SelfAssessmentRatingService implements GrailsConfigurationAware {

    MessageSource messageSource

    List<Map> setupAssessmentRatings

    @Override
    void setConfiguration(Config co) {
        List selfAssessmentRatings = co.getProperty('setup.selfAssessmentRatings', List, null)
        setupAssessmentRatings = selfAssessmentRatings as List<Map>
    }

    /**
     * Saves a SelfAssessmentRating record for each one specified in the application config.
     * This method gets called if there are no SelfAssessmentRating records saved.
     */
    def createRatingsFromConfig() {
        if (setupAssessmentRatings == null || setupAssessmentRatings.empty) {
            log.info("Skipping creating SelfAssessmentRatings because none were specified " +
                "in the config: 'setup.selfAssessmentRatings'")
            return
        }

        log.info("Saving ${setupAssessmentRatings.size()} new SelfAssessmentRating records")
        for (Map map in setupAssessmentRatings) {
            // SelfAssessmentRating is a domain class
            SelfAssessmentRating newRating = new SelfAssessmentRating()
            newRating.rating = map.rating as Integer
            newRating.englishText = map.englishText
            newRating.translationKey = map.translationKey
            newRating.save(failOnError: true)
            // Verify we have that translation. This will throw an exception if the translation is not present.
            messageSource.getMessage(newRating.translationKey, [].toArray(), Locale.default)
        }
    }
}

Here is the default config value for setup.selfAssessmentRatings; this is in the root of application.yml so it applies to all Grails environments:

setup.selfAssessmentRatings:
    - {rating: 1, translationKey: "example.selfAssessment.noExperience", englishText: "No Experience or Knowledge"}
    - {rating: 2, translationKey: "example.selfAssessment.someExperience", englishText: "Some Experience or Knowledge"}
    - {rating: 3, translationKey: "example.selfAssessment.functionIndependently", englishText: "Able to function independently in this area"}

And I have those three messages defined in grails-app/i18n/messages.properties:

example.selfAssessment.noExperience=No Experience or Knowledge
example.selfAssessment.someExperience=Some Experience or Knowledge
example.selfAssessment.functionIndependently=Able to function independently in this area

My integration tests all pass in CircleCI (./gradlew -Dgrails.env=circleci integrationTest), but on my local machine I get the following error for each integration test:

org.springframework.context.NoSuchMessageException: No message found under code 'example.selfAssessment.noExperience' for locale 'en_US'.
    at org.springframework.context.support.AbstractMessageSource.getMessage(AbstractMessageSource.java:161)
    at com.hclabs.ojt.step.SelfAssessmentRatingService.$tt__createRatingsFromConfig(SelfAssessmentRatingService.groovy:46)

Does anyone know how I can get my integration tests to pass again locally ?

Is there an argument I could add or an environment variable to set when calling ./gradlew integrationTest on my local machine so that Grails can find the messages in grails-app/i18n/messages.properties?