AMBARI-5425. Set -server in java opts in mapred-site.xml and tez-site.xml.(vbrodetskyi)

ambari-server/src/main/resources/stacks/HDP/2.0.6.GlusterFS/services/MAPREDUCE2/configuration/mapred-site.xml

@@ -263,7 +263,7 @@
 
   <property>
     <name>yarn.app.mapreduce.am.admin-command-opts</name>
-    <value>-Djava.net.preferIPv4Stack=true -Dhadoop.metrics.log.level=WARN</value>
+    <value>-server -Djava.net.preferIPv4Stack=true -Dhadoop.metrics.log.level=WARN</value>
     <description>
       Java opts for the MR App Master processes for admin purposes.
       It will appears before the opts set by yarn.app.mapreduce.am.command-opts and
@@ -295,12 +295,12 @@
 
   <property>
     <name>mapreduce.admin.map.child.java.opts</name>
-    <value>-Djava.net.preferIPv4Stack=true -Dhadoop.metrics.log.level=WARN</value>
+    <value>-server -Djava.net.preferIPv4Stack=true -Dhadoop.metrics.log.level=WARN</value>
   </property>
 
   <property>
     <name>mapreduce.admin.reduce.child.java.opts</name>
-    <value>-Djava.net.preferIPv4Stack=true -Dhadoop.metrics.log.level=WARN</value>
+    <value>-server -Djava.net.preferIPv4Stack=true -Dhadoop.metrics.log.level=WARN</value>
   </property>
 
   <property>