Grails 3.3.10 error running integration test for a service

### Task List

- [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. grails create-app test
2. grails create-domain-class com.cabolabs.security.User
3. added username and password String fields
4. grails generate-app com.cabolabs.security.User
5. grails create-service com.cabolabs.cloud.BalanceUpdate
6. grails create-integration-test com.cabolabs.cloud.BalanceUpdate
7. grails test-app com.cabolabs.cloud.BalanceUpdate -integration

That runs OK, the test fails because of the default code, that is not important.

Then I started to add references to services in the UserController, and the BalanceUpdateService, like mailService from the mail plugin.

The test worked as before.

Then I added this line, which I have extensively used in many controllers of my original project:

def config = grailsApplication.config

With that line, the whole thing felt apart and got the error:

```
org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'com.cabolabs.security.UserController': Instantiation of bean failed; nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.cabolabs.security.UserController]: Constructor threw exception; nested exception is java.lang.IllegalStateException: No thread-bound request found: Are you referring to request attributes outside of an actual web request, or processing a request outside of the originally receiving thread? If you are actually operating within a web request and still receive this message, your code is probably running outside of DispatcherServlet/DispatcherPortlet: In this case, use RequestContextListener or RequestContextFilter to expose the current request.
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1160)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1104)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:511)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:481)
at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:312)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:308)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197)
at org.springframework.context.support.AbstractApplicationContext.getBean(AbstractApplicationContext.java:1080)
at org.spockframework.spring.SpringMockTestExecutionListener.beforeTestMethod(SpringMockTestExecutionListener.java:54)
at org.spockframework.spring.AbstractSpringTestExecutionListener.beforeTestMethod(AbstractSpringTestExecutionListener.java:23)
at org.springframework.test.context.TestContextManager.beforeTestMethod(TestContextManager.java:269)
at org.spockframework.spring.SpringTestContextManager.beforeTestMethod(SpringTestContextManager.java:54)
at org.spockframework.spring.SpringInterceptor.interceptSetupMethod(SpringInterceptor.java:45)
at org.spockframework.runtime.extension.AbstractMethodInterceptor.intercept(AbstractMethodInterceptor.java:28)
at org.spockframework.runtime.extension.MethodInvocation.proceed(MethodInvocation.java:87)
at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecuter.runTestClass(JUnitTestClassExecuter.java:114)
at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassExecuter.execute(JUnitTestClassExecuter.java:57)
at org.gradle.api.internal.tasks.testing.junit.JUnitTestClassProcessor.processTestClass(JUnitTestClassProcessor.java:66)
at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:51)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:35)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:32)
at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:93)
at org.gradle.api.internal.tasks.testing.worker.TestWorker.processTestClass(TestWorker.java:109)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:35)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
at org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:147)
at org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:129)
at org.gradle.internal.remote.internal.hub.MessageHub$Handler.run(MessageHub.java:404)
at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:63)
at org.gradle.internal.concurrent.StoppableExecutorImpl$1.run(StoppableExecutorImpl.java:46)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
Caused by: org.springframework.beans.BeanInstantiationException: Failed to instantiate [com.cabolabs.security.UserController]: Constructor threw exception; nested exception is java.lang.IllegalStateException: No thread-bound request found: Are you referring to request attributes outside of an actual web request, or processing a request outside of the originally receiving thread? If you are actually operating within a web request and still receive this message, your code is probably running outside of DispatcherServlet/DispatcherPortlet: In this case, use RequestContextListener or RequestContextFilter to expose the current request.
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:154)
at org.springframework.beans.factory.support.SimpleInstantiationStrategy.instantiate(SimpleInstantiationStrategy.java:89)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateBean(AbstractAutowireCapableBeanFactory.java:1152)
... 34 more
Caused by: java.lang.IllegalStateException: No thread-bound request found: Are you referring to request attributes outside of an actual web request, or processing a request outside of the originally receiving thread? If you are actually operating within a web request and still receive this message, your code is probably running outside of DispatcherServlet/DispatcherPortlet: In this case, use RequestContextListener or RequestContextFilter to expose the current request.
at org.springframework.web.context.request.RequestContextHolder.currentRequestAttributes(RequestContextHolder.java:131)
at grails.web.api.WebAttributes$Trait$Helper.currentRequestAttributes(WebAttributes.groovy:45)
at grails.web.api.WebAttributes$Trait$Helper.getGrailsAttributes(WebAttributes.groovy:54)
at grails.web.api.WebAttributes$Trait$Helper.getGrailsApplication(WebAttributes.groovy:134)
at org.springframework.beans.BeanUtils.instantiateClass(BeanUtils.java:142)
... 36 more
```

I fixed the issue by changing grailsApplication.config to Holders.config, though grailsApplication.config works OK, so I guess this is a bug related to the integration test run, just wanted to report it so the core team can take a look.

### Expected Behaviour

Test run without any exceptions.

### Actual Behaviour

Got exceptions before the test isi actually executed.

### Environment Information

- **Operating System**: Linux Mint 19.3
- **Grails Version:** 3.3.10
- **JDK Version:** 8

### Example Application

[service-integration-tests.zip](https://github.com/grails/grails-core/files/7181511/service-integration-tests.zip)

Start with the attached service-integration-tests.zip and reproduce the failure using the listed Grails commands, especially the BalanceUpdate integration test. Inspect how grailsApplication.config is accessed from UserController during test setup and compare it with the reported Holders.config workaround. Done means the integration test starts without the request-bound exception and its existing behavior remains intact.

Written by the indexing model from the issue text.