使用log4j-over-slf4j不能兼容的问题

MonitorLog.java 的 static 块中显式用到了 log4j的不常用类：FileAppender、DailyRollingFileAppender

而 log4j.jar 作者后续的 log4j-over-self4j.jar，没有这两个类(NoClassDefFoundError)，
只有 log4j 标准 API 用法的同名类 和 Appender/RollingFileAppender 等有限类。

感觉MetaStatLog实际没多大用处，这个是否可以直接去掉？
或者改为简单地写文件，不依赖具体的log的实现，或者改用slf4j？

Start with the static block in MonitorLog.java and inspect how MetaStatLog uses FileAppender and DailyRollingFileAppender. Confirm the failure with log4j-over-slf4j, then determine and document a chosen compatibility approach; done means startup no longer raises NoClassDefFoundError with that dependency.

Written by the indexing model from the issue text.