Set the useTrailingSlashMatch to true for tests

The Spring MVC changed the default behavior for trailing slash match
with https://github.com/spring-projects/spring-framework/issues/28552.
This causes failures in Spring Security's tests.

Setting the `useTrailingSlashMatch` to `true` ensures that Spring
Security will work for users who have modified the default configuration.
Specifing the request mapper with trailing slash path ensures that the tests
are successful when default behavior is used.

Closes gh-11451

test/src/test/java/org/springframework/security/test/web/servlet/request/SecurityMockMvcRequestPostProcessorsAuthenticationStatelessTests.java

@@ -95,7 +95,7 @@ public class SecurityMockMvcRequestPostProcessorsAuthenticationStatelessTests {
 		@RestController
 		static class Controller {
 
-			@RequestMapping
+			@RequestMapping("/")
 			String hello() {
 				return "Hello";
 			}

test/src/test/java/org/springframework/security/test/web/servlet/request/SecurityMockMvcRequestPostProcessorsTestSecurityContextStatelessTests.java

@@ -89,7 +89,7 @@ public class SecurityMockMvcRequestPostProcessorsTestSecurityContextStatelessTes
 		@RestController
 		static class Controller {
 
-			@RequestMapping
+			@RequestMapping("/")
 			String hello() {
 				return "Hello";
 			}