The WAR file will not include a 'netbeans' folder, which would normally be there, including a very long list of subfolders with NetBeans JAR files, for each of the NetBeans Platform modules, because of the jnlp.platform.codebase property above.
The above includes a "netbeans/" link, which is only shown if the property described above has NOT been set. Therefore, to verify that everything is as expected, i.e., you're using the 'bits.netbeans.org' location for hosting the NetBeans Platform JARs, you should see this instead:
Ether way, clicking the "master.jnlp" link should result in your application deploying via Java Web Start.
The index.html file should contain a line like this:
<a href="master.jnlp">Launch the application</a>
Now click "Build JNLP Application" again and the content of your "build" folder will be turned into your WAR file (i.e., in the "dist" folder, exactly as before), which will now include your index.html file.
Then replace the old WAR file on GlassFish with your new one, which should result in the launcher link being displayed in the browser, together with whatever else you included in the index.html file:
Also, because of the above property in the platform.properties file, all the relevant NetBeans modules will be downloaded, which therefore will not need to be done again for any other application using those modules.