Move /application to /actuator

Change the endpoint default path from `/application` to `/actuator`.

Fixes gh-10970

spring-boot-samples/spring-boot-sample-webflux/src/test/java/sample/webflux/SampleWebFluxApplicationTests.java

@@ -55,7 +55,7 @@ public class SampleWebFluxApplicationTests {
 
 	@Test
 	public void testActuatorStatus() {
-		this.webClient.get().uri("/application/health").accept(MediaType.APPLICATION_JSON)
+		this.webClient.get().uri("/actuator/health").accept(MediaType.APPLICATION_JSON)
 				.exchange().expectStatus().isOk().expectBody()
 				.json("{\"status\":\"UP\"}");
 	}