YARN-11599. Incorrect log4j properties file in SLS sample conf (#6220) Contributed by Junfan Zhang.

Reviewed-by: Shilun Fan <slfan1989@apache.org>
Signed-off-by: Shilun Fan <slfan1989@apache.org>

hadoop-tools/hadoop-sls/src/main/sample-conf/log4j.properties

@@ -16,4 +16,4 @@ log4j.appender.test.Target=System.out
 log4j.appender.test.layout=org.apache.log4j.PatternLayout
 log4j.appender.test.layout.ConversionPattern=%d{ABSOLUTE} %5p %c{1}:%L - %m%n
 
-log4j.logger=NONE, test
+log4j.rootLogger=WARN, test