Revert "Remove level_tag property"

This reverts commit 5a067f0.

Author: Joseph Kim

dev/ant_build/build-mdt.xml

@@ -1,5 +1,5 @@
 <!--
-    Copyright (c) 2018, 2019 IBM Corporation and others.
+    Copyright (c) 2018 IBM Corporation and others.
     All rights reserved. This program and the accompanying materials
     are made available under the terms of the Eclipse Public License v2.0
     which accompanies this distribution, and is available at
@@ -10,8 +10,7 @@
 -->
 
 <project name="mdt_build" default="generateOpenMDTUpdateSite">
-	<!-- Obtain the property from the build definition -->
-    <!-- property name="level_tag" value="19.01"/ -->
+    <property name="level_tag" value="19.01"/>
     <property name="delegate.build.dir" location="${basedir}/../" />
     <property name="disable.run.executeMetatypeValidation" value="true"/>
     <property name="disable.run.unzipIfixReleaseZip" value="true"/>