Spring Ensure context caching works properly during AOT runtime in the TestContext framework

The MergedContextConfiguration may differ between AOT processing time and AOT run time. For example, Spring Boot "disables" selected ContextCustomizer implementations during AOT runtime execution (see https://github.com/spring-projects/spring-boot/commit/0f325f98b5f0ad07d404a41cc172ad33879a8ecf).

In light of that, we need to ensure that context caching works properly during AOT runtime execution when the MergedContextConfiguration differs from what was produced during the AOT processing phase.