Cleanup SDK packaging: remove alias build files.

tools/scripts/AndroidManifest.alias.template

@@ -1,4 +1,8 @@
 <?xml version="1.0" encoding="utf-8"?>
+<!--
+ALIAS PROJECTS ARE CURRENT NOT SUPPORTED.
+THIS FILE IS CURRENTLY BROKEN AND SHOULD NOT BE USED.
+-->
 <manifest xmlns:android="http://schemas.android.com/apk/res/android"
       package="PACKAGE"
       android:versionCode="1"