Polish "Avoid using deprecated NCSARequestLog"

See gh-16987

spring-boot-project/spring-boot-actuator-autoconfigure/src/main/java/org/springframework/boot/actuate/autoconfigure/web/servlet/ServletManagementChildContextConfiguration.java

@@ -202,16 +202,18 @@ class ServletManagementChildContextConfiguration {
 
 		private void customizeRequestLog(CustomRequestLog requestLog) {
 			if (requestLog.getWriter() instanceof RequestLogWriter) {
-				RequestLogWriter writer = (RequestLogWriter) requestLog.getWriter();
+				customizeRequestLogWriter((RequestLogWriter) requestLog.getWriter());
+			}
+		}
+
+		private void customizeRequestLogWriter(RequestLogWriter writer) {
 			String filename = writer.getFileName();
 			if (StringUtils.hasLength(filename)) {
 				File file = new File(filename);
-					file = new File(file.getParentFile(),
+				file = new File(file.getParentFile(), customizePrefix(file.getName()));
-							customizePrefix(file.getName()));
 				writer.setFilename(file.getPath());
 			}
 		}
-		}
 
 	}