Load MockitoConfiguration parent-first to make it work in continuous testing

[famod]

Moves the class to a separate new module to reduce the blast radius.

Fixes #23109

What I don't get is why it works without this in regular testing. So maybe there is another, less ugly fix?

/cc @aloubyansky

[famod]

Btw, the move to a separate module is not just a precautionary measure, it's actually required to avoid failures like:

2022-01-22T01:39:12.0674921Z [INFO] Running io.quarkus.it.panache.DuplicateMethodTest
2022-01-22T01:39:18.0949236Z [ERROR] Tests run: 2, Failures: 0, Errors: 1, Skipped: 1, Time elapsed: 6 s <<< FAILURE! - in io.quarkus.it.panache.DuplicateMethodTest
2022-01-22T01:39:18.0952409Z [ERROR] io.quarkus.it.panache.DuplicateMethodTest.shouldNotDuplicateMethodsInRepository  Time elapsed: 0.092 s  <<< ERROR!
2022-01-22T01:39:18.0955347Z java.lang.RuntimeException: java.util.ServiceConfigurationError: io.quarkus.test.junit.buildchain.TestBuildChainCustomizerProducer: io.quarkus.test.junit.mockito.internal.UnremoveableMockTestBuildChainCustomizerProducer not a subtype
2022-01-22T01:39:18.0956822Z 	at io.quarkus.test.junit.QuarkusTestExtension.throwBootFailureException(QuarkusTestExtension.java:626)
2022-01-22T01:39:18.0957726Z 	at io.quarkus.test.junit.QuarkusTestExtension.interceptTestClassConstructor(QuarkusTestExtension.java:699)
2022-01-22T01:39:18.0958850Z 	at org.junit.jupiter.engine.execution.ExecutableInvoker.lambda$invoke$0(ExecutableInvoker.java:105)
2022-01-22T01:39:18.0960039Z 	at org.junit.jupiter.engine.execution.InvocationInterceptorChain$InterceptedInvocation.proceed(InvocationInterceptorChain.java:106)
[...]

See also: https://github.com/famod/quarkus/actions/runs/1731130863

[famod]

Would be nice to have this in 2.7.0 (so I added the backport label), but let's see what comes up during review.

[stuartwdouglas]

The problematic code is here: https://github.com/mockito/mockito/blob/main/src/main/java/org/mockito/internal/configuration/ClassPathLoader.java#L60

In regular testing the mockito classes are still on the system class path, so the config class can still be loaded (but not from the Quarkus CL). In continuous testing mode they are not on the class path, so it cannot be loaded.

Moving this to parent first means that it will be added to the system class path and everything works as expected. This is the correct thing to do anyway IMHO, as it was already being used in a parent first manner.