[bs-153] Don't expose classes as resource

Made classpath:/[static,resourecs,public] available instead. Some
sample apps had to change so probably some gs-* guides etc as well?

[Fixes #51368907]

spring-zero-samples/spring-zero-sample-web-ui/src/test/java/org/springframework/zero/sample/web/ui/SampleWebUiApplicationTests.java

@@ -78,7 +78,7 @@ public class SampleWebUiApplicationTests {
 	@Test
 	public void testCss() throws Exception {
 		ResponseEntity<String> entity = getRestTemplate().getForEntity(
-				"http://localhost:8080/css/bootstrap.min.css", String.class);
+				"http://localhost:8080/resources/css/bootstrap.min.css", String.class);
 		assertEquals(HttpStatus.OK, entity.getStatusCode());
 		assertTrue("Wrong body:\n" + entity.getBody(), entity.getBody().contains("body"));
 	}