Integration Tests for `kie-maven-plugin` fail on a fresh clone due to `drools-ruleunits-engine` not being found

On a fresh clone, with a fresh local Maven repository, run:

`mvn clean install -pl :kie-maven-plugin -am`

You'll see this error

```
[ERROR] Failed to execute goal org.apache.maven.plugins:maven-invoker-plugin:3.2.1:run (integration-test) on project kie-maven-plugin: 1 build failed. See console output above for details
```

Scrolling up, you'll see:

```
[INFO] Building: kie-maven-plugin-test-kjar-14-ruleunits/pom.xml
[INFO]   The build exited with code 1. See /Users/tiagobento/apache/incubator-kie-drools/kie-maven-plugin/target/it/kie-maven-plugin-test-kjar-14-ruleunits/build.log for details.
[INFO]           kie-maven-plugin-test-kjar-14-ruleunits/pom.xml .. FAILED (1.4 s)
```

Inside the [build.log](https://github.com/user-attachments/files/26876988/build.log), you'll find:

```
Could not find artifact org.drools:drools-ruleunits-engine:jar:999-SNAPSHOT
```

---

Due to PR checks and local builds being sequential, coincidentally `drools-ruleunits-engine` ends up being built before `kie-maven-plugin`, which makes it available in the local Maven repository, and therefore causes the tests to pass.

Building `kie-maven-plugin`'s stack in isolation exposes the problem.

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