Spring-boot-maven-plugin repackage overwrites original JAR in SpringBoot integration-test modules - use exec classifier to fix

### Describe the bug

When using `spring-boot-maven-plugin` to repackage a JAR in SpringBoot integration-test modules, the plugin by default **replaces the original artifact** with the fat repackaged JAR. This breaks downstream Maven builds that depend on the original (thin) JAR - for example, when another module or step tries to use the JAR as a dependency or classpath artifact.

The fix is to configure the `repackage` goal with the `exec` classifier, which makes the plugin produce the fat JAR as a _secondary_ artifact (e.g., `*-exec.jar`) while keeping the original JAR as the primary Maven artifact.

### Expected behavior

The `spring-boot-maven-plugin` `repackage` goal should be configured with `<classifier>exec</classifier>` so that:
- The original thin JAR remains the primary Maven artifact.
- The fat/executable JAR is available as a secondary artifact with the `exec` classifier (e.g., `my-app-exec.jar`).

### Actual behavior

The original JAR is replaced by the repackaged fat JAR, which can break downstream builds or test classpath resolution.

### How to Reproduce?

1. Build any SpringBoot integration-test module that uses `spring-boot-maven-plugin` with the `repackage` goal (no classifier).
2. Observe that the original JAR in `target/` is replaced by the fat repackaged JAR.
3. Any downstream Maven step that attempts to use the artifact as a regular JAR dependency fails or behaves unexpectedly.

### Output of `uname -a` or `ver`

Darwin Vishnus-MacBook-Pro.local 24.1.0 Darwin Kernel Version 24.1.0: Thu Oct 10 21:06:57 PDT 2024; root:xnu-11215.41.3~3/RELEASE_ARM64_T6041 arm64

### Output of `java -version`

openjdk version "21.0.2" 2024-01-16 LTS IBM Semeru Runtime Open Edition 21.0.2.0 (build 21.0.2+13-LTS)

### GraalVM version (if different from Java)

_No response_

### Kogito version or git rev (or at least Quarkus version if you are using Kogito via Quarkus platform BOM)

_No response_

### Build tool (ie. output of `mvnw --version` or `gradlew --version`)

Apache Maven 3.9.16

### Additional information

_No response_

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