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-tomcat/src/test/java/sample/tomcat/NonAutoConfigurationSampleTomcatApplicationTests.java

@@ -36,7 +36,6 @@ import org.springframework.context.annotation.Configuration;
 import org.springframework.context.annotation.Import;
 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;
@@ -48,7 +47,6 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 @RunWith(SpringRunner.class)
 @SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
-@DirtiesContext
 public class NonAutoConfigurationSampleTomcatApplicationTests {
 
 	@Autowired

spring-boot-samples/spring-boot-sample-tomcat/src/test/java/sample/tomcat/SampleTomcatApplicationTests.java

@@ -37,7 +37,6 @@ import org.springframework.http.HttpHeaders;
 import org.springframework.http.HttpMethod;
 import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
-import org.springframework.test.annotation.DirtiesContext;
 import org.springframework.test.context.junit4.SpringRunner;
 import org.springframework.util.StreamUtils;
 
@@ -51,7 +50,6 @@ import static org.assertj.core.api.Assertions.assertThat;
  */
 @RunWith(SpringRunner.class)
 @SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
-@DirtiesContext
 public class SampleTomcatApplicationTests {
 
 	@Autowired