Support "*" mapping in MockMvc filter registration

Prior to this commit, configuring a Servlet filter in MockMvc with a
defined mapping would only consider "/*" as a catch-all pattern.

This commit relaxes this rule by also accepting "*" mappings.

Closes gh-28041

spring-test/src/test/java/org/springframework/test/web/servlet/setup/MockMvcFilterDecoratorTests.java

@@ -95,7 +95,7 @@ public class MockMvcFilterDecoratorTests {
 
 	@Test
 	public void matchPathMappingAll() throws Exception {
-		assertFilterInvoked("/test", "/*");
+		assertFilterInvoked("/test", "*");
 	}
 
 	@Test