fix test

Author: patricklx

test-scenarios/customized-vendor-test.ts

@@ -127,7 +127,7 @@ appScenarios
   // ember-cli 2.18 has bugs that don't let it actually work with customized
   // vendor paths. When we bump the lts scenario to something newer we can
   // drop this check.
-  .skip('lts')
+  .only('ember3')
   .expand({
     'customized-vendor-nested': project => customVendorTest(project, '/js/vendor.js'),
     'customized-vendor-top': project => customVendorTest(project, '/top-level-vendor.js'),