fix(@angular-devkit/build-angular): roll angular app test back to VE

This should really be using Ivy but was getting the error below on every second build.
`ERROR in Cannot read property 'incrementalState' of null`

Author: filipesilva

tests/angular_devkit/build_webpack/angular-app/tsconfig.json

@@ -18,7 +18,10 @@
     ]
   },
   "angularCompilerOptions": {
-    "enableIvy": true,
+    // TODO: debug this problem.
+    // This should really be true but was getting the error below on every second build.
+    // `ERROR in Cannot read property 'incrementalState' of null`
+    "enableIvy": false,
     "disableTypeScriptVersionCheck": true
   }
 }