Deprecate JUnit 4 support

[fmbenhassine]

Related to spring-projects/spring-framework#34794

[Coen90]

@fmbenhassine I would like to assign this task.

[fmbenhassine]

@Coen90 Sure thank you for your offer to help!

I don't think there much to do here, except updating javadocs

spring-batch/spring-batch-test/src/main/java/org/springframework/batch/test/context/SpringBatchTest.java

Lines 47 to 83 in 15f3637

	* A typical usage of this annotation with JUnit 4 is like the following:
	*
	* <pre class="code">
	* &#064;RunWith(SpringRunner.class)
	* &#064;SpringBatchTest
	* &#064;ContextConfiguration(classes = MyBatchJobConfiguration.class)
	* public class MyBatchJobTests {
	*
	* &#064;Autowired
	* private JobLauncherTestUtils jobLauncherTestUtils;
	*
	* &#064;Autowired
	* private JobRepositoryTestUtils jobRepositoryTestUtils;
	*
	* &#064;Autowired
	* private Job jobUnderTest;
	*
	* &#064;Before
	* public void setup() {
	* this.jobRepositoryTestUtils.removeJobExecutions();
	* this.jobLauncherTestUtils.setJob(this.jobUnderTest); // this is optional if the job is unique
	* }
	*
	* &#064;Test
	* public void testMyJob() throws Exception {
	* // given
	* JobParameters jobParameters = this.jobLauncherTestUtils.getUniqueJobParameters();
	*
	* // when
	* JobExecution jobExecution = this.jobLauncherTestUtils.launchJob(jobParameters);
	*
	* // then
	* Assert.assertEquals(ExitStatus.COMPLETED, jobExecution.getExitStatus());
	* }
	*
	* }
	* </pre>

,

spring-batch/spring-batch-test/src/main/java/org/springframework/batch/test/StepScopeTestExecutionListener.java

Line 40 in 52064c0

* @RunWith(SpringJUnit4ClassRunner.class)

(maybe somewhere else as well) and reference docs with a deprecation note.