YARN-9668. UGI conf doesn't read user overridden configurations on RM and NM startup. (Contributed by Jonanthan Hung)

Addendum to fix 3.0 build

hadoop-yarn-project/hadoop-yarn/hadoop-yarn-server/hadoop-yarn-server-nodemanager/src/main/java/org/apache/hadoop/yarn/server/nodemanager/NodeManager.java

@@ -43,6 +43,7 @@ import org.apache.hadoop.fs.permission.FsPermission;
 import org.apache.hadoop.metrics2.lib.DefaultMetricsSystem;
 import org.apache.hadoop.security.Credentials;
 import org.apache.hadoop.security.SecurityUtil;
+import org.apache.hadoop.security.UserGroupInformation;
 import org.apache.hadoop.service.CompositeService;
 import org.apache.hadoop.util.ExitUtil;
 import org.apache.hadoop.util.GenericOptionsParser;