Move back to JUnit 4 until SUREFIRE-1614 has been resolved

See gh-14736
See gh-14737
See gh-14738

spring-boot-samples/spring-boot-sample-tomcat-multi-connectors/src/test/java/sample/tomcat/multiconnector/SampleTomcatTwoConnectorsApplicationTests.java

@@ -18,7 +18,8 @@ package sample.tomcat.multiconnector;
 
 import org.apache.catalina.Service;
 import org.apache.catalina.connector.Connector;
-import org.junit.jupiter.api.Test;
+import org.junit.Test;
+import org.junit.runner.RunWith;
 import sample.tomcat.multiconnector.SampleTomcatTwoConnectorsApplicationTests.Ports;
 
 import org.springframework.beans.factory.annotation.Autowired;
@@ -34,6 +35,7 @@ import org.springframework.context.ApplicationListener;
 import org.springframework.context.annotation.Import;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
+import org.springframework.test.context.junit4.SpringRunner;
 
 import static org.assertj.core.api.Assertions.assertThat;
 
@@ -43,7 +45,7 @@ import static org.assertj.core.api.Assertions.assertThat;
  * @author Brock Mills
  * @author Andy Wilkinson
  */
-
+@RunWith(SpringRunner.class)
 @SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
 @Import(Ports.class)
 public class SampleTomcatTwoConnectorsApplicationTests {