Polish AutoConfigurationMetadataLoader

Align to other final classes, the protected modifier is meaningless.

See gh-45020

Signed-off-by: Yanming Zhou <zhouyanming@gmail.com>

spring-boot-project/spring-boot-autoconfigure/src/main/java/org/springframework/boot/autoconfigure/AutoConfigurationMetadataLoader.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2012-2019 the original author or authors.
+ * Copyright 2012-2025 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -33,7 +33,7 @@ import org.springframework.util.StringUtils;
  */
 final class AutoConfigurationMetadataLoader {
 
-	protected static final String PATH = "META-INF/spring-autoconfigure-metadata.properties";
+	private static final String PATH = "META-INF/spring-autoconfigure-metadata.properties";
 
 	private AutoConfigurationMetadataLoader() {
 	}