AMBARI-13395. Add ambari properties for specifying user inactivity timeout (smohanty)

ambari-server/conf/unix/ambari.properties

@@ -87,6 +87,10 @@ ulimit.open.files=10000
 # Server HTTP settings
 server.http.session.inactive_timeout=1800
 
+# user inactivity timeout setting
+user.inactivity.timeout.default=0
+user.inactivity.timeout.role.readonly.default=0
+
 # to skip service checks during deploy
 skip.service.checks=false