Samples cleanup

- Modifying dependencies to starter-web with tomcat exclusion plus
  alternative servlet container instead of manual dependency on
  spring-webmvc as it is the preferrable way to use alternative servlet
  container
- Previously RestTemplate with ssl was configured manually in tests - now
  it rellies on autoconfiguration - changed this for multi-connector test
  and added test to ensure that ssl autoconfiguration is working
- Most samples with alterntative servlet containers used some kind of
  service reading property and returning default since it wasn't
  configured - removed it, since it is not specific to using alternative
  servlet containers.

See gh-10548

spring-boot-samples/spring-boot-sample-undertow-ssl/src/test/java/sample/undertow/ssl/SampleUndertowSslApplicationTests.java

@@ -23,9 +23,9 @@ import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.boot.test.context.SpringBootTest;
 import org.springframework.boot.test.context.SpringBootTest.WebEnvironment;
 import org.springframework.boot.test.web.client.TestRestTemplate;
+import org.springframework.boot.web.server.AbstractConfigurableWebServerFactory;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
-import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.junit4.SpringRunner;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -37,11 +37,17 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 @RunWith(SpringRunner.class)
 @SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
-@DirtiesContext
 public class SampleUndertowSslApplicationTests {
 
 	@Autowired
 	private TestRestTemplate restTemplate;
+	@Autowired
+	private AbstractConfigurableWebServerFactory webServerFactory;
+
+	@Test
+	public void testSsl() {
+		assertThat(this.webServerFactory.getSsl().isEnabled()).isTrue();
+	}
 
 	@Test
 	public void testHome() throws Exception {