Align test with Spring MVC's internals once again

The internals have been updated so that the field that was originally
used, interceptors, can be used again.

This reverts commit 2a1bca6.

spring-boot-actuator/src/test/java/org/springframework/boot/actuate/autoconfigure/EndpointWebMvcAutoConfigurationTests.java

@@ -148,7 +148,7 @@ public void onDifferentPort() throws Exception {
 		assertContent("/endpoint", ports.get().management, "endpointoutput");
 		List<?> interceptors = (List<?>) ReflectionTestUtils.getField(
 				this.applicationContext.getBean(EndpointHandlerMapping.class),
-				"handlerInterceptors");
+				"interceptors");
 		assertEquals(1, interceptors.size());
 		this.applicationContext.close();
 		assertAllClosed();