Deprecated JUnit4

[Coen90]

This PR primarily focuses on reflecting the deprecation of JUnit 4 within the Spring Batch project.

Here's a breakdown of the changes:

• Documentation Update (testing.adoc):

  • A note has been added to the testing documentation explicitly stating that Spring Batch no longer supports JUnit 4 and recommends users migrate to JUnit Jupiter.

• Javadoc Updates in Test Listeners (JobScopeTestExecutionListener.java, StepScopeTestExecutionListener.java):

  • The example usage in the Javadoc for both JobScopeTestExecutionListener and StepScopeTestExecutionListener has been modified.
  • The @RunWith(SpringJUnit4ClassRunner.class) annotation, specific to JUnit 4, has been removed from these examples.
  • The @SpringJUnitConfig annotation, which is typically used with JUnit 5, has been added to these examples.

• Javadoc and Example Removal in SpringBatchTest.java:

  • The detailed Javadoc example demonstrating how to use @SpringBatchTest with JUnit 4 has been removed.
  • A clear statement has been added to the Javadoc for the @SpringBatchTest annotation, indicating that "JUnit4 is deprecated in Spring Batch 6.0.0 and will be removed in a future release."

In essence, these changes remove JUnit 4 specific examples and guidance, update documentation to reflect its deprecation, and point towards JUnit 5 (Jupiter) as the recommended testing framework.