Add Spring Boot GraalVM integration test

As highlighted in several issue reports (e.g., apache/logging-log4j2#3770, apache/logging-log4j2#3790), while Log4j Core’s native configuration process works well in GraalVM, issues may arise with Spring Boot’s custom **reconfiguration** process during the execution of native images.

To ensure that Log4j Core is fully compatible with Spring Boot, we propose adding a dedicated GraalVM integration test for Spring Boot. This will help verify that Log4j Core functions correctly when integrated with Spring Boot’s native image support.

Begin by locating the repository's Spring Boot and GraalVM native-image integration-test entry points; the issue names no files or existing test. Run the relevant native-image test setup, then confirm that Log4j Core remains functional during Spring Boot's custom reconfiguration in a native image.

Written by the indexing model from the issue text.