fix log level is null in Slf4j and fix not valid in Log4j2

[xixingya]

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  fix 应用初始化启动后，使用telnet查看“日志框架运行时”抛NPE #12650

[xixingya]

@AlbumenJ hello,I only fix the slf4j is null but I have not have a good idea on set level

[xixingya]

1

[AlbumenJ]

[xixingya]

@AlbumenJ in this class we can not use dubbo log,may be sout err is a idea

[sonarcloud]

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