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-ssl/src/main/java/sample/tomcat/ssl/web/SampleController.java

@@ -16,15 +16,13 @@
 
 package sample.tomcat.ssl.web;
 
-import org.springframework.stereotype.Controller;
 import org.springframework.web.bind.annotation.GetMapping;
-import org.springframework.web.bind.annotation.ResponseBody;
+import org.springframework.web.bind.annotation.RestController;
 
-@Controller
+@RestController
 public class SampleController {
 
 	@GetMapping("/")
-	@ResponseBody
 	public String helloWorld() {
 		return "Hello, world";
 	}